List of Kamen Rider Build characters

File:KRBuild transform.jpg

The main protagonists of the series: (from left to right) Sento Kiryū, Kazumi Sawatari, and Ryūga Banjō.

Kamen Rider Build (仮面ライダービルド, Kamen Raidā Birudo) is a Japanese tokusatsu drama and the 28th entry in the Kamen Rider series.

nascita

nascita is a café owned by Sōichi Isurugi where he lives with his daughter Misora. After meeting Sento, they shelter him there as well as allow him to live in the basement. They also shelter Ryūga after Sento rescues him from the authorities. However, the revelation of Sōichi Isurugi being Blood Stalk, and had been possessed by the evil martian Evolto as the worst part all along compromises the café's status as a safehouse for a short while until he leaves Touto.

Sento Kiryū

Sento Kiryū (桐生 戦兎, Kiryū Sento) is a young man in his 20s who has prodigious mental abilities. Prior to the start of the series, he was found by Sōichi Isurugi in an alley, missing all of his memories except for one where he was being experimented on by Gentoku as Night Rogue. Sōichi gives Sento his name and convinced the youth to help him fight the Smash in the hopes of regaining his memories. However, Sento's search while also helping Ryūga clear his name leads to him learning of a series of shocking revelations that Sōichi was the mastermind behind the events that ruined both his and Ryūga's lives, followed by a defeated Gentoku revealing Sento's true identity.

Sento was originally one of the founding members of Faust, Takumi Katsuragi (葛城 巧, Katsuragi Takumi), a scientist whose infamous reputation earned him the moniker of "The Devil's Scientist" (悪魔の科学者, Akuma no kagakusha) by his colleagues. His late father, Shinobu Katsuragi (葛城 忍, Katsuragi Shinobu) was the leader of the Mars exploration group alongside Sōichi Isurugi and oversaw Project Evol (プロジェクトエビル, Purojekuto Eboru) following the circumstances of Ryūga's birth before research on the Evol Driver ended when Shinobu committed suicide following the Skywall incident. Takumi revived the experiment as Project Build (プロジェクトビルド, Purojekuto Birudo) to honor his father's memory, but was banned for conducting unethical human experimentations by using a mutative by-product of the Skywall known as Nebula Gas (ネビュラガス, Nebyura Gasu) as a means of evolving humanity. Sometime after developing the sample bottle-like Fullbottles (フルボトル, Furubotoru) and the Transteam Guns, as well as starting the final tests of Project Build, Takumi developed a change of heart after learning that Faust has been compromised through Evolto's influence through Sōichi. He quits the organization on September 5th, deciding to seek redemption by finishing the Project Build technology to protect the innocent while developing the spoutbag-like Sclashjellies (スクラッシュゼリー, Sukurasshu Zerī) and the Sclash Driver. On the day he quit, Takumi hired a musician named Tarō Satō (佐藤 太郎, Satō Tarō) to deliver a drug for him, also hiring Ryūga as he knows Evolto would eventually come for him. Four days later, refusing to return to Faust so his technology could be used for war, a confrontation with Evolto led to Takumi being knocked out after the alien switched out his Build Driver for a prototype. Evolto then murdered Tarō while using his powers to alter Takumi's face and memories to be experimented on by Gentoku, later using his host's identity as Sōichi to take Takumi under his care to have him test the Project Build technology's full capabilities.

Prior to his memory loss, Takumi learned his reality is separate from the prime Kamen Rider world, like Decade's world, and assisted his former Touto colleague Kaisei Mogami in building the Enigma system for interdimensional travel. While in the prime Kamen Rider world, Takumi tested Project Build while seeking out Kamen Rider Ex-Aid to analyze his abilities. Though he accidentally killed Kamen Rider Genm in a case of mistaken identity, Takumi succeeds a few days later by extracting Ex-Aid's abilities into a large Fullbottle after defeating Kamen Rider Para-DX during the events of Kamen Rider Ex-Aid the Movie: True Ending. But Takumi learned of Kaisei's intent to cause a convergence between the two realities and stopped him, resulting in Kaisei's body being damaged. In Heisei Generations Final, having no recollection of stealing Ex-Aid's abilities, Sento assumed the event to be a dream prior to learning his true identity as Takumi.

Sento is able to transform into Kamen Rider Build by using the Build Driver (ビルドドライバー, Birudo Doraibā) in conjunction with the Fullbottles, which contain a liquified element created by the refinement of Nebula Gas. As Build, he initially fought Faust and the Smash in the hopes of regaining his memories before learning his true identity and resolve to stop the abuse of his technology. Though level-headed and compassionate, Sento is egotistical with a dangerous temper when provoked by his most hated enemies.

In order to access each of his forms, Build must combine two Fullbottles, one organic (based on an animal or person) and one inorganic (based on an object), in the Build Driver to transform. Certain combinations allow him to assume either strong compatibility forms called a Best Match (ベストマッチ, Besuto Matchi), which can perform the Vortex Finish (ボルテックフィニッシュ, Borutekku Finisshu) finishing move, or weaker random forms called a Trial Form (トライアルフォーム, Toraiaru Fōmu), which can perform the Vortex Attack (ボルテックアタック, Borutekku Atakku) finishing move. His default Best Match is RabbitTank Form (ラビットタンクフォーム, Rabitto Tanku Fōmu), also known as the "Moonsault of Steel" (鋼のムーンサルト, Hagane no Mūnsaruto). This form is achieve by using the Rabbit (ラビット, Rabitto) Fullbottle, which gives him superhuman reflexes along with spring-like Rabbit Foot Shoes (ラビットフットシューズ, Rabitto Futto Shūzu) on his left leg, and the Tank (タンク, Tanku) Fullbottle that provides Build with the tread-like Tank Roller Shoes (タンクローラーシューズ, Tanku Rōrā Shūzu) on his right leg for enhanced kicking. Build later uses the beverage can-like RabbitTank Sparkling (ラビットタンクスパークリング, Rabitto Tanku Supākuringu) to assume an upgraded version of his default form called RabbitTank Sparkling Form (ラビットタンクスパークリングフォーム, Rabitto Tanku Supākuringu Fōmu), also known as the "Bubbling and Bursting" (シュワッと弾ける, Shuwatto Hajikeru). The form first appearing in the Kamen Rider Heisei Generations Final movie, Build's RabbitTank Sparkling Form allows him to utilize all of his Best Match weapons.

• GorillaMond Form (ゴリラモンドフォーム, Goriramondo Fōmu), also known as the "Shining Destroyer" (輝きのデストロイヤー, Kagayaki no Desutoroiyā), is a Best Match that uses the Gorilla (ゴリラ, Gorira) Fullbottle, which gives Build superhuman strength and the Muscle Glove (マッスルグローブ, Massuru Gurōbu) on his right arm, and the Diamond (ダイヤモンド, Daiyamondo) for increased durability and BLD Prism Glove (BLDプリズムグローブ, BLD Purizumu Gurōbu) on his left arm. Sento initially used this as Takumi in episode 44 of Kamen Rider Ex-Aid and its film sequel True Ending before the bottles were emptied out by Evolto's deception, only for Sento to refill them with Misora's help.
• HawkGatling Form (ホークガトリングフォーム, Hōku Gatoringu Fōmu), also known as the "Rampage of the Skies" (天空の暴れん坊, Tenkū no Abarenbō), is a Best Match that uses the Taka (タカ, Hawk) Fullbottle, which provides Build with the airfoil-like Solstall Wings (ソレスタルウィング, Soresutaru Wingu), and the Gatling (ガトリング, Gatoringu) Fullbottle, which enhances Build's accuracy. In this form or any Trial Match using either Fullbottle, Build is armed with the Hawk Gatlinger (ホークガトリンガー, Hōku Gatoringā) submachine gun that he uses for hisFull Bullet (フルバレット, Furu Baretto) finishing move.
• NinninComic Form (ニンニンコミックフォーム, Ninnin Komikku Fōmu), also known as the "Sneaky Entertainer" (忍びのエンターテイナー, Shinobi no Entāteinā), is a Best Match that uses the Ninjya (ニンジャ, Ninja) Fullbottle, equipping Build with the sash-like Onmitsu Scarf (オンミツスカーフ, Onmitsu Sukāfu) on his back for enhanced agility, and the Comic (コミック, Komikku) Fullbottle, which enables Build to project illusionary images with his forehead. In this form or any Trial Match using either Fullbottle, Build is armed with the 4Koma Ninpoutou (4コマ忍法刀, Yon Koma Ninpōtō, Four-frame Ninja Sword) katana, which allows him to perform one of two finishing moves: Fire Jutsu (火遁の術, Katon no Jutsu, Art of Fire Releasing) or Wind Jutsu (風遁の術, Fūton no Jutsu, Art of Wind Releasing). The 4Koma Ninpoutou can also be used to initiate one of two special attacks: Clone Jutsu (分身の術, Bunshin no Jutsu, Art of Cloning) or Stealth Jutsu (隠れ身の術, Kakuremi no Jutsu, Art of Camouflage).
• RocketPanda Form (ロケットパンダフォーム, Roketto Panda Fōmu), also known as the "Flying Monotone" (ぶっ飛びモノトーン, Buttobi Monotōn), is a Best Match that uses the Panda (パンダ) Fullbottle, equipping equips Build with the Giant Scratcher (ジャイアントスクラッチャー, Jaianto Sukuratchā) claw on his right arm, and the Rocket (ロケット, Roketto) Fullbottle, which equips Build with the missile-like Space Ride Arm (スペースライドアーム, Supēsu Raido Āmu) on his left arm for projectile launching.
• FireHedgehog Form (ファイヤーヘッジホッグフォーム, Faiyā Hejjihoggu Fōmu), also known as the "Rescue Kenzan" (レスキュー剣山, Resukyū Kenzan), is a Best Match that uses the Harinezumi (ハリネズミ, Hedgehog) Fullbottle, equiping Build with the spiky Spine Knuckle (スパインナックル, Supain Nakkuru) on his right arm, and the Shoubousha (消防車, Shōbōsha, Fire engine) Fullbottle, which arms build with the hose-like Multi Deluge Gun (マルチデリュージガン, Maruchi Deryūji Gan) on his left arm for either shooting fire or spraying water.
• LionCleaner Form (ライオンクリーナーフォーム, Raion Kurīnā Fōmu), also known as the "Maned Cyclone" (たてがみサイクロン, Tategami Saikuron), is a Best Match that uses the Lion (ライオン, Raion), which arms Build with the wrist guard-like Gold Lio Gauntlet (ゴルドライオガントレット, Gorudo Raio Gantoretto) on his right arm, and the Soujiki (掃除機, Sōjiki, Vacuum cleaner) Fullbottle which equips Build with both the hoover-like Long Range Cleaner (ロングレンジクリーナー, Rongu Renji Kurīnā) on his left arm which vacuums attacks that are stored in the canister-like Trash Converter (トラッシュコンバーター, Torasshu Konbātā) on his left shoulder. Outside its compatibility with the Build Driver, the Lion Fullbottle can loaded into the Build Phone (ビルドフォン, Birudo Fon) for it to transform into the Machine Builder (マシンビルダー, Mashin Birudā) motorcycle.
• KeyDragon Form (キードラゴンフォーム, Kī Doragon Fōmu), also known as the "Sealed Fantasia" (封印のファンタジスタ, Fūin no Fantajisuta), is a Best Match uses the Dragon (ドラゴン, Doragon), which arms Build with Drago Rush Arm (ドラゴラッシュアーム, Dorago Rasshu Āmu)and Fang of Raid (ファングオブレイド, Fangu Obu Reido) spike projections, and the Lock (ロック, Rokku) Fullbottle that equips Build with the battering ram-like Bind Master Key (バインドマスターキー, Baindo Masutā Kī) and BLD Security Shoulder (BLDセキュリティショルダー, Bī Eru Dī Sekyuriti Shorudā) on his left arm. The form is occasional used due to the strain the Dragon Fullbottle places on Sento's body before it was given to Ryūga.
• KaizokuRessya Form (海賊レッシャーフォーム, Kaizoku Resshā Fōmu, PirateTrain Form), also known as the "Punctual Rebel" (定刻の反逆者, Teikoku no Hangyakusha), is a Best Match that uses the Kaizoku (海賊, Pirate) Fullbottle, which arms Build with Multi Sail Mantle (マルチセイルマント, Maruchi Seiru Manto) on his right shoulder for wind-power conversion, and the Densya (電車, Densha, Train) Fullbottle that wquips Build with the wrist guard-like Train Gauntlet (トレインガントレット, Torein Gantoretto) on his left arm for increased speed. In this form or any Trial Match using either Fullbottle, Build is uses the bladed bow-like Kaizoku Hassyar (カイゾクハッシャー, Kaizoku Hasshā), which allows him to perform the Kaizoku Densya (海賊電車, Kaizoku Densha) finishing move. The Kaizoku Hassyar can also be used to initiate one of three special attacks: Kakueki Densya (各駅電車, Kakueki Densha, All Station Train), Kyukou Densya (急行電車, Kyūkō Densha, Express Train), or Kaisoku Densya (快速電車, Kaisoku Densha, Rapid-Service Train).
• OctopusLight Form (オクトパスライトフォーム, Okutopasu Raito Fōmu), also known as the "Lightning Technician" (稲妻テクニシャン, Inazuma Tekunishan), is a Best Match that is accessed via the Octopus (オクトパス, Okutopasu) Fullbottle, which gives Build with the tentacle-like Twist Lash Arm (ツイストラッシュアーム, Tsuisuto Rasshu Āmu) on his right shoulder, and the Light (ライト, Raito) Fullbottle which equips Build with both the fuse-like Shade Breaker (シェードブレイカー, Shēdo Bureikā) and beacon-like BLD Light Bulb Shoulder (BLDライトバルブショルダー, BLD Raito Barubu Shorudā) on his left arm to emit bright flashes.
• PhoenixRobo Form (フェニックスロボフォーム, Fenikkusu Robo Fōmu), also known as the "Immortal Weapon" (不死身の兵器, Fujimi no Heiki), is a Best Match that was introduced in Kamen Rider Heisei Generations Final: Build & Ex-Aid with Legend Rider. The Best Match utilizes the Phoenix (フェニックス, Fenikkusu) Fullbottle, which arms Build Flame Reviber (フレイムリヴァイバー, Fureimu Rivaibā) gauntlet and Empirial Wings (エンパイリアルウィング, Enpairiaru Uingu), and the Robot (ロボット, Robotto) Fullbottle that equips Build with the mechanical arm Demolition One (デモリションワン, Demorishon Wan) for dismantling and crushing targets which his BLD Arsenal Shoulder (BLDアーセナルショルダー, Bī Eru Dī Āsenaru Shorudā) convert into his personal robot troops.
• SmaphoWolf Form (スマホウルフフォーム, Sumaho Urufu Fōmu), also known as the "Connected Lone Wolf" (つながる一匹狼, Tsunagaru Ippiki Ōkami), is a Best Match that was among the forms Sento acquired while as Takumi. The Best Match is accessed via the Wolf (ウルフ, Urufu) Fullbottle, arming Build with the Wolfatal Claw (ウルフェイタルクロー, Urufeitaru Kurō) and animal instinct, and the Smapho (スマホ, Sumaho, Smartphone) Fullbottle which equips Build with the buckler-like Build Pad Shield (ビルドパッドシールド, Birudo Paddo Shīrudo) on his left arm for either defending capabilities or selecting a recommended attack enhancement. Although the Build Pad Shield cracks upon sustaining a strong attack, it can repair itself. Befitting its identical appearance to the Build Phone, the Build Pad Shield can also function in the same manner, with the exception of Bike Mode.
• RoseCopter Form (ローズコプターフォーム, Rōzu Koputā Fōmu), also known as the "Passionate Fan" (情熱の扇風機, Jōnetsu no Senpūki) is a Best Match that is accessed via the Rose (ローズ, Rōzu) Fullbottle, allowing allows Build to manipulate vines or fire thorn projections with Ibalash Arm (イバラッシュアーム, Ibarasshu Āmu), and the Helicopter (ヘリコプター, Herikoputā) Fullbottle that equips Build with the Batrotor Blade (バトローターブレード, Batorōtā Burēdo) helicopter rotor for flight or removable weapon.
• ToraUFO Form (トラユーフォーフォーム, Tora Yūfō Fōmu), also known as the "Unidentified Jungle Hunter" (未確認ジャングルハンター, Mikakunin Janguru Hantā), is a Best Match that is accessed via Tora (トラ, Tiger) Fullbottle, increasing Build's speed while arming him with the BLD Tora Fight Glove (BLDトラファイトグローブ, Bī Eru Dī Tora Faito Gurōbu) and the BLD Tiger Head Shoulder (BLDタイガーヘッドショルダー, Bī Eru Dī Taigā Heddo Shorudā), and the UFO (UFO, Yūfō) Fullbottle which allows allows Build to conjure an UFO projection to ride on.
• KujiraJet Form (クジラジェットフォーム, Kujira Jetto Fōmu), also known as the "Sky-Flying Big Wave" (天駆けるビッグウェーブ, Amakakeru Biggu Wēbu), is a Best Match that is accessed via the Kujira (クジラ, Whale) Fullbottle, arming him with the BLD Spout Glove (BLDスパウトグローブ, Bī Eru Dī Supauto Gurōbu) to manipulate water currents, and the Jet (ジェット, Jetto) Fullbottle which enables Build ability to do skywalk while creating create mini Jets to attack.
• KirinCyclone Form (キリンサイクロンフォーム, Kirin Saikuron Fōmu), also known as the "Towering Storm-Caller" (嵐を呼ぶ巨塔, Arashi o Yobu Kyotō), is a Best Match that is accessed via the Kirin (キリン, Giraffe) Fullbottle, equipping Build with the horn-like Giraffe Neck Thrust (ジラフネットラスト, Jirafu Nekku Turasuto) to create giraffe's neck-energy punches, and the Senpuki (扇風機, Senpūki, Fan) Fullbottle that enables Build to create tornados.
• TurtleWatch Form (タートルウォッチフォーム, Tātoru Wotchi Fōmu), also known as the "Armored Time Hopper" (時を駆ける甲冑, Toki o Kakeru Katchū), is a Best Match that is accessed via the Turtle (タートル, Tātoru) Fullbottle and the Watch (ウォッチ, Wotchi) Fullbottle. This form first appears in Kamen Rider Build Episode 21 off scene.

Build's main weapon is the Drill Crusher (ドリルクラッシャー, Doriru Kurasshā), which has a sword-like Blade Mode (ブレードモード, Burēdo Mōdo) and a firearm-like Gun Mode (ガンモード, Gan Mōdo). The Drill Crusher can also hold a Fullbottle for Build to perform its Vortex Break (ボルテックブレイク, Borutekku Bureiku) finishing move. After defeating a Smash, Build can extract its element liquid into a powerless version of a Fullbottle known as an Empty Bottle (エンプティボトル, Enputi Botoru) to be purified into a new Fullbottle to utilize its abilities to either access one of his forms or charge one of his weapons. Even without the Build Driver, Sento (or anyone else) is able to channel a Fullbottle's power simply by activating it.

Sento later acquires the item called Hazard Trigger (ハザードトリガー, Hazādo Torigā), which he created as Takumi before it fell into Sōichi's hands, to transform into a black-colored version of Build called Hazard Form (ハザードフォーム, Hazādo Fōmu) whose upgraded Super Best Match (スーパーベストマッチ, Sūpā Besuto Matchi) forms are stronger then RabbitTank Sparkling Form to being equal to Sclash Driver-using Kamen Riders. But the Hazard Trigger induces a berserker side-effect from it usage, causing Sento to hesitate using it while he and Nariaki Utsumi added a self-destruct mechanism as a measure. But when Misora awakened her full ability which allows her to purify the Hazard Levels of Nebula Gas, effectively negating the berserker effects of the Hazard Trigger which also leads to Sento creating the FullFull RabbitTank Bottle.

• FullFull RabbitTank Bottle (フルフルラビットタンクボトル, Furu Furu Rabitto Tanku Botoru) is a 2-in-1 Fullbottle device which can switch between the full forms of Rabbit and Tank Fullbottles, granting Build access to use each of the Fullbottles' full potentials. This Fullbottle negates the side-effect of the Hazard Trigger. Its main weapon is the Fullbottle Buster (フルボトルバスター, Furubotoru Basutā) and by inserting up to four Fullbottles into the side of its barrel, it can activate several special finishing moves. It has two modes: Buster Blade Mode and Buster Cannon Mode.
  • RabbitRabbit Form (ラビットラビットフォーム, Rabitto Rabitto Fōmu), also known as "Crimson Speedy Jumper" (紅のスピーディージャンパー, Kurenai no Supīdī Janpā), is a form which utilizes the full potential of Rabbit Fullbottle powers. His finishing move in this form is the Hazard Finish: RabbitRabbit Finish (ハザードフィニッシュ ラビットラビットフィニッシュ, Hazādo Finisshu Rabitto Rabitto Finisshu).
  • TankTank Form (タンクタンクフォーム, Tanku Tanku Fōmu), also known as "Blue Warrior of Steel" (鋼鉄のブルーウォーリア, Kōtetsu no Burū Wōria), is a form which utilizes the full potential of Tank Fullbottle powers. His finishing move in this form is the Hazard Finish: TankTank Finish (ハザードフィニッシュ タンクタンクフィニッシュ, Hazādo Finisshu Tanku Tanku Finisshu).

Sento eventually re-learns of Evolto's existence, forced to hand him the Evol Driver when the alien had Gentoku take his father Taizan hostage. Once obtaining the Evol Driver, Evolto poisons Sento as part of his plan to have Ryūga willingly become his vessel. Ryūga agrees and maintains his will long enough to cure Sento, who would attempt to save him by reverse-engineering a container from the Pandora Box that he installed into his Build Driver to extract Evolto and then trigger the belt's self-destruct to destroy the entity at the cost of his own life. But Evolto took advantage and possesses Sento, causing his hair to whiten while used by Evolto to repair his Evolto-Trigger.

These forms only appear in other media:

• KumaTelevi Form (クマテレビフォーム, Kuma Terebi Fōmu), also known as the "Honey High Vision" (はちみつハイビジョン, Hachimitsu Hai Bijon), is a Best Match that is accessed via the Kuma (クマ, Bear) and Televi (テレビ, Terebi, Television) Fullbottles. This Best Match is currently exclusive to Kamen Rider Build: Birth! KumaTelevi!! Vs. Kamen Rider Grease.
• SameBike Form (サメバイクフォーム, Same Baiku Fōmu), also known as the "Solo-Running Hunter" (独走ハンター, Dokusō Hantā), is a Best Match that is accessed via the Same (サメ, Shark) and Bike (バイク, Baiku) Fullbottles. This Best Match is exclusive to Kamen Rider Build: Raising the Hazard Level With 7 Best Matches.
• BeetleCamera Form (ビートルカメラフォーム, Bītoru Kamera Fōmu), also known as the "Scoop King of the Forest" (密林のスクープキング, Mitsurin no Sukūpu Kingu), is a Best Match that is accessed via the Kabutomushi (カブトムシ, Rhinoceros beetle) and Camera (カメラ, Kamera) Fullbottles. This Best Match is exclusive to the Ganbarizing video game.
• DogMic Form (ドッグマイクフォーム, Doggu Maiku Fōmu), also known as the "Big Sound of Healing" (癒しの大爆音, Iyashi no Daibakuon), is a Best Match that is accessed via the Dog (ドッグ, Doggu) and Mic (マイク, Maiku) Fullbottles. This Best Match is exclusive to the Ganbarizing video game.
• MerryChristmas Form (メリークリスマスフォーム, Merī Kurisumasu Fōmu), also known as the "Holy Emissary" (聖なる使者, Seinaru Shisha), is a Best Match that is accessed via the Santa Claus (サンタクロース, Santa Kurōsu) and Cake (ケーキ, Kēki) Fullbottles. This Best Match is exclusive to the Ganbarizing video game.
• Legend Rider Best Match Forms: Much like Kamen Rider Decade before him, Build can shapeshift into the primary forms of any of the previous lead Kamen Riders via Best Match function between two corresponding Fullbottles based the previous lead Riders' motifs. In the Kamen Rider Battle: Ganbarizing video game, if Build uses different Legend Rider Fullbottles for Trial Forms, Build will not shapeshift into the previous lead Kamen Riders. Most Legend Rider-themed Fullbottles have a compatible Best Match with one of Build's regular Fullbottles.
  • Ex-Aid Form (エグゼイドフォーム, Eguzeido Fōmu): By using the Doctor (ドクター, Dokutā) and Game (ゲーム, Gēmu) Fullbottles, Build shapeshifts into Kamen Rider Ex-Aid Action Gamer Level 2 where he is armed with the Gashacon Breaker. When purified, the Ex-Aid (エグゼイド, Eguzeido) Fullbottle split into the two Fullbottles. This Best Match is exclusive to Kamen Rider Heisei Generations Final: Build & Ex-Aid with Legend Rider.
  • Ghost Form (ゴーストフォーム, Gōsuto Fōmu): By using the Obake (おばけ, Ghost) and Parka (パーカー, Pākā) Fullbottles, Build shapeshifts into Kamen Rider Ghost Ore Damashii where he is armed with the Gan Gun Saber. This Best Match is currently exclusive to the Ganbarizing video game.
  • Gaim Form (鎧武フォーム, Gaimu Fōmu): By using the Orange (オレンジ, Orenji) and Lock Fullbottles, Build shapeshifts into Kamen Rider Gaim Orange Arms where he is armed with both the Daidamaru and the Musou Saber. This Best Match is currently exclusive to the Ganbarizing video game.
  • Wizard Form (ウィザードフォーム, Wizādo Fōmu): By using the Mahoutsukai (魔法使い, Mahōtsukai, Magician) and Diamond Fullbottles, Build shapeshifts into Kamen Rider Wizard Flame Style where he is armed with the Wizarswordgun. This Best Match is currently exclusive to the Ganbarizing video game.
  • Fourze Form (フォーゼフォーム, Fōze Fōmu): By using the Yujou (友情, Yūjō, Friendship) and Rocket Fullbottles, Build shapeshifts into Kamen Rider Fourze Base States where he gains the ability to manifest an Astroswitch's Fourze Module onto his limbs. This Best Match is currently exclusive to the Ganbarizing video game.
  • OOO Form (オーズフォーム, Ōzu Fōmu): By using the Taka and Medal (メダル, Medaru) Fullbottles, Build shapeshifts into Kamen Rider OOO Tatoba Combo where he is armed with both the Medajalibur and the Medagabryu. This Best Match is currently exclusive to the Ganbarizing video game.
  • Double Form (ダブルフォーム, Daburu Fōmu): By using the Tantei (探偵, Detective) and USB Memory (USBメモリ, Yū Esu Bī Memori) Fullbottles, Build shapeshifts into Kamen Rider Double CycloneJoker. This Best Match is currently exclusive to the Ganbarizing video game.
  • Decade Form (ディケイドフォーム, Dikeido Fōmu): By using the Card (カード, Kādo) and Camera Fullbottles, Build shapeshifts into Kamen Rider Decade where he is armed with the Ride Booker. This Best Match is currently exclusive to the Ganbarizing video game.
  • Den-O Form (電王フォーム, Den'ō Fōmu): By using the Momotaros (モモタロス, Momotarosu) and Densya Fullbottles, Build shapeshifts into Kamen Rider Den-O Sword Form where he is armed with the DenGasher. This Best Match is currently exclusive to the Ganbarizing video game.

Sento Kiryū is portrayed by Atsuhiro Inukai (犬飼 貴丈, Inukai Atsuhiro), who also portrays Tarō Satō, while Takumi Katsuragi is portrayed by Yukiaki Kiyama (木山 廉彬, Kiyama Yukiaki).

Ryūga Banjō

Ryūga Banjō (万丈 龍我, Banjō Ryūga) is a 23-year old ex-fighter who was born in Yokohama with few memories of his parents due the trauma of their accidental deaths ten years ago. After being banned for life from competition for cheating, he was supposed to work with the former Touto Institute researcher and founder of Faust, Takumi Katsuragi. What Ryūga was unaware that he was actually half Martian as the result of his mother Yuri Banjō (万丈 優里, Banjō Yuri), a security guard at Namba Industries, being impregnated with a gene sample of Evolto's original body that the company brought from Mars. Takumi learned of this while quitting Faust, hiring Ryūga under false pretenses as he knew Evolto intends to transfer himself from Sōichi Isurugi into Ryūga. But Takumi's plan backs fires on September 9th with Evolto having Ryūga arrested for Takumi's apparent death with 10-year jail sentence. While in prison, Ryūga was kidnapped by Faust's agent Nabeshima to be used for Faust's experiment. Somehow, he managed to escape before the experimentation completely turned him into a Smash and with his memories intact. After escaping, he is found by Sento who takes him under his protection in the hopes of getting clues to his past. Ryūga was forced to use a variety of disguises whenever aiding Sento until the truth behind Takumi's supposed death is finally revealed, later learning his true origins from Vernage while having been manipulated by Evolto's machinations to strengthen his alien genes as part of the entity's plan to possess him.

As a result of his hybrid physiology and the experiments done on him by Faust, Ryūga possesses physical strength that classified him to have the power of Hazard Levels 2 and 3. This, combined with his own natural fighting abilities, makes him a powerful fighter. However, he is also shown to not be very bright and easily provoked, often with comical results. When assisting Build in his battles, he occasionally borrows the Drill Crusher and rides his own motorcycle. Ryūga was later given the Dragon Fullbottle by Sento to honor his late girlfriend, Kasumi Ogura, who was turned into a Smash by Faust and then had to be killed by Build. He can use the Dragon Fullbottle to increase his physical strength even further. Sento later creates a small robotic dragon-like companion to assist Ryūga known as the Cross-Z Dragon (クローズドラゴン, Kurōzu Doragon), which is capable of breathing fire, extracting poisons from the infected’s body and utilizing a Fullbottle's powers.

Initially fighting as Sento's sidekick, events leading to the temporary loss of all but two Fullbottles to Night Rogue forced Sento to give Ryūga a copy of the Build Driver. By inserting the Cross-Z Dragon and Dragon Fullbottle into the Build Driver once his Nebula Gas has reached Hazard Level 3, he transforms into Kamen Rider Cross-Z (仮面ライダークローズ, Kamen Raidā Kurōzu) where his finishing move is the Dragonic Finish (ドラゴニックフィニッシュ, Doragonikku Finisshu). Unlike Build, Cross-Z can utilize the Dragon Fullbottle's powers due to the Cross-Z Dragon negating its side effects. His main weapon is the sword-like Beat Closer (ビートクローザー, Bīto Kurōzā), which allows him to initiate one of three special attacks: Smash Hit (スマッシュヒット, Sumasshu Hitto), Million Hit (ミリオンヒット, Mirion Hitto), or Mega Hit (メガヒット, Mega Hitto). Like the Drill Crusher, the Beat Closer can also hold a Fullbottle for Cross-Z to perform one of three Special Tune (スペシャルチューン, Supesharu Chūn) finishing moves: Smash Slash (スマッシュスラッシュ, Sumasshu Surasshu), Million Slash (ミリオンスラッシュ, Mirion Surasshu), or Mega Slash (メガスラッシュ, Mega Surasshu).

During the invasion of Touto by Hokuto, Ryūga gains from Sento the Sclash Driver (スクラッシュドライバー, Sukurasshu Doraibā) for him to use in conjunction with the Dragon Sclashjelly to transform into an evolved version of Cross-Z known as Kamen Rider Cross-Z Charge (仮面ライダークローズチャージ, Kamen Raidā Kurōzu Chāji) where his finishing move is the Scrap Break (スクラップブレイク, Sukurappu Bureiku). Cross-Z Charge's main weapon is the Twin Breaker (ツインブレイカー, Tsuin Bureikā), which has a laser gun-like Beam Mode (ビームモード, Bīmu Mōdo) and a jackhammer-like Attack Mode (アタックモード, Atakku Mōdo). Unlike the Drill Crusher and Beat Closer, the Twin Breaker can hold up to two Fullbottles and Sclashjellies, as well as either the RabbitTank Sparkling or the Cross-Z Dragon, for Cross-Z Charge to perform its finishing move. Inserting an organic Fullbottle into the Sclash Driver allows Cross-Z Charge to initiate the Charge Crash (チャージクラッシュ, Chāji Kurasshu) special attack. However, usage of the Sclash Driver exposes Ryūga to unpurified Nebula Gas which causes him to become more violent as a side effect until his determination and guilt over causing Sento to use the Hazard Trigger finally gives him the strength to overcome the effects. When Sōichi is about to kill an awaken Vernage, Ryūga risks his life saving the queen, at the cost of destroying the Dragon Jelly, disabling his ability to transform into Cross-Z Charge.

As the war against Seito and Namba continues, Ryūga learns his true nature from Vernage while creates the Cross-Z Magma Knuckle (クローズマグマナックル, Kurōzu Maguma Nakkuru) to stabilize the power of the Dragon Magma Fullbottle that Sōichi accidentally created from the Dragon Sclashjelly. Ryūga uses it with Build Driver to become Kamen Rider Cross-Z Magma (仮面ライダークローズマグマ, Kamen Raidā Kurōzu Maguma), also known as Extreme Heat Muscle (極熱筋肉, Gokunetsu Kinniku), in this way Cross-Z Magma own Cross-Z Magma Knuckle that allows him to give strong blows of fire, he is even able to use it in his primary form of Cross-Z. His finishing move in the Magma form is the Volcanic Finish (ボルケニックフィニッシュ, Borukenikku Finisshu). Also thanks to the fact that Ryūga has alien origins, he has extraordinary abilities as one of them is to raise his hazard level faster than usual and use the power of the Pandora Box. Following being possessed by Evolto before the entity transfers into Sento's body, Ryūga learns he lose his ability to transform as a result of Evolto having extracted his genes from his former host.

• Dragon (ドラゴン, Doragon) Fullbottle: In addition to being able to access the Cross-Z form with the Cross-Z Dragon and this Fullbottle, also when using this Fullbottle together with Dragon Sclashjelly in the Twin Breaker makes a powerful finish, can also be used in the Beat Closer to create fire around the sword to attack. If used alone, this Fullbottle can grant the user blue fire blows.
  • Dragon Sclashjelly: When using the Sclashjelly Dragon in the Twin Breaker a powerful attack is made. Destroyed along with Schlash Driver by Stalk, but the former would soon evolved into Dragon Magma Fullbottle.
    • Dragon Magma (ドラゴンマグマ, Doragon Maguma) Fullbottle: In addition to being able to become Cross-Z Magma with this Fullbottle, Cross-Z can use it to attack by inserting it into the Cross-Z Magma Knuckle, which allows him to attack with a fire dragon.
• Lock (ロック, Rokku) Fullbottle: Often used to activate Special Tune from Beat Closer, creating dark blue fire steam to burn enemy or creating energy chains to bind enemy.
• Taka (タカ, Hawk) Fullbottle: Manifest a pair of wings so that Cross-Z Charge can fly, also this Fullbottle can be used in the Cross-Z Magma Knuckle to make powerful final blow, by projecting wings of energy to the sides to then attack.

Ryūga Banjō is portrayed by Eiji Akaso (赤楚 衛二, Akaso Eiji).

Misora Isurugi

Misora Isurugi (石動 美空, Isurugi Misora) is a 19-year old girl and Sōichi's daughter who works as Sento's assistant, gaining a supernatural power after being rendered comatose for seven years from being exposed to the Pandora Box sometime after the Skywall Disaster. She was kidnapped by Faust to use in their traumatic experimentation until Sōichi managed to rescue her a year ago. Fearing that Faust is still trailing her, she remained in nascita while using her online idol identity Mii-tan (みーたん, Mītan) to gather Smash intel and occasionally money from her fanbase. But Misora was unaware that her father is actually a high-ranked Faust agent who used her, Sento and Ryūga as their tools to create a Kamen Rider army within Touto. Though Sento, Ryūga and Sawa decide to spare Misora from knowing her father's activities in Faust upon learning he is Blood Stalk, she is hinted to have learned this revelation as well while being driven to despair. She later uses her powers to cure Taizan Himuro of Sōichi's poison so he can resume his duties as Touto's prime minister and soon discovers that her father is actually being possessed by Evolto, the true villain committing the crimes using her father as a vessel.

Due to being exposed to the Pandora Box, wearing a bracelet that originated from Mars, Misora possesses the ability to purify and enhance Nebula Gas which made her a target for Faust in the first place. Initially, the usage of the ability exhausts her to the point of a week-long sleep before Sento developed a machine that would reduce her burden. Misora later awakens her full potential when nearly killed by a berserk Build Hazard Form, allowing her to purify the higher Nebula Gas concentrations like those from the Hazard Trigger itself. Sento would use her power to create the FullFull RabbitTank Bottle and Fullbottle Buster to negate the Hazard Trigger's side-effects. During Seito's invasion, the bracelet is revealed to house an entity known as Vernage.

Misora Isurugi is portrayed by Kaho Takada (高田 夏帆, Takada Kaho). As a child, Misora is portrayed by Noel Moriyama (森山 のえる, Moriyama Noeru).

Sawa Takigawa

Sawa Takigawa (滝川 紗羽, Takigawa Sawa) is a 27-year old freelance journalist dedicated to learning about Build and the Smash since being saved by the former after he saved her from the Needle Smash, later learning of the Kamen Rider's true identity as Sento and providing him with assistance. While later revealed to be a spy for Namba, Sawa is actually using her position to covertly learn the truth behind the cover-up of an industrial accident at Namba Heavy Industries that killed her father and ten others. When Misora exposed her cover, Sawa is punished by being turned into the octopus-themed Stretch Smash (ストレッチスマッシュ, Sutoretchi Sumasshu) before she is defeated by Ryūga with Sento extracting the Nebula Gas from her system. After that, she decides to atone for her actions and join forces with Sento's group to fight against Namba and Faust. During the time she spent with them, Sawa becomes protective of Misora, especially after learning of the younger woman's backstory.

Sawa is later revealed to be a Namba Child agent, the story about her father being a fabrication, but the familial bonds she made with Sento and the others gave her a reason to life and influenced her decision to completely cut ties with Namba. Sawa accomplishes this by aiding Sento in the ploy to trick Namba by giving him a fragment of Sento's research on the FullFull RabbitTank Bottle while Kazumi rescues the Nabeshima family whom Namba was held hostage as leverage against her.

Sawa Takigawa is portrayed by Yukari Taki (滝 裕可里, Taki Yukari).

Hokuto troopers

Kazumi Sawatari

Kazumi Sawatari (猿渡 一海, Sawatari Kazumi) is a 29-year old soldier from Hokuto who was originally a farm owner until the Skywall Disaster ruined his livlihood as he sacrificed his life savings to help out his workers (the Hokuto Three Crows). In hopes of obtaining more financial support, Kazumi willingly signed for Hokuto's military and underwent Faust's human experimentation. Lying about suffering memory loss, Kazumi's continued use of the Sclash Driver turned him into a bloodthirsty fighter, though he is shown to have his urge for battle under control as shown by him retaining a sense of morality in refusing to allow harm to unarmed civilians and caring for the welfare of the Hokuto Three Crows. It is also revealed that he is an avid fan of Misora Isurugi, whom he recognizes as the net-idol Mii-tan. Having first infiltrated Touto during the events of Heisei Generations Final to steal Build's Phoenix and Robot Fullbottles for Hokuto, Kazumi is deployed to lead the Hokuto army to invade Touto. The conflict eventually ends in a decisive battle with Grease defeated by Build HawkGatling Hazard and Cross-Z Charge saving Grease from being killed at the last second when Sento goes berserk thanks to the Hazard Trigger. During Seito's attack on his country and Touto, he decides to join forces with Sento and Ryūga, having realized that he had been another pawn in Faust and Namba's plot. At time when Namba and Evolto enact their plan to bring humanity to chaos, one of Kazumi's farmers were being held hostage by Namba, until Gentoku freed them, despite unable to get himself freed from Namba's destructive chip in his body for disobeying him, with Kazumi finally reunite with his co-farmers safely in Touto's shelter.

By using the Sclash Driver (スクラッシュドライバー, Sukurasshu Doraibā) in conjunction with the Robot Sclashjelly, Kazumi transforms into Kamen Rider Grease (仮面ライダーグリス, Kamen Raidā Gurisu) where his finishing move is the Scrap Finish (スクラップックフィニッシュ, Sukurappu Finisshu). Grease's main weapon is the Twin Breaker (ツインブレイカー, Tsuin Bureikā), which has a laser gun-like Beam Mode (ビームモード, Bīmu Mōdo) and a jackhammer-like Attack Mode (アタックモード, Atakku Mōdo). Unlike the Drill Crusher and Beat Closer, the Twin Breaker can hold up to two Fullbottles and Sclashjellies, as well as either the RabbitTank Sparkling or the Cross-Z Dragon, for Grease to perform its finishing move. Inserting an inorganic Fullbottle into the Sclash Driver allows Grease to initiate the Discharge Crash (ディスチャージクラッシュ, Disuchāji Kurasshu) special attack.

• Helicopter (ヘリコプター, Herikoputā) Fullbottle: Manifests a propeller on Grease's right arm for flying capabilities, also when using with the Sclashjelly robot in the Twin Breaker creates propellers of yellow energy and are thrown to the enemy. If used by itself, this Fullbottle can enable the user to perform an energy punch that is strong enough to destroy a Hazard Smash.
• Keshigomu (消しゴム, Eraser) Fullbottle: Provides Grease and other passengers cover for a quick retreat.
• Lock (ロック, Rokku) Fullbottle: Allow Grease creating chains both of his hands to bind enemies.
• Televi (テレビ, Terebi, Television) Fullbottle: Inserting this Fullbottle along with the Fullbottle Smapho in the Twin Breaker, create a giant screen and launch smartphones.
• Smapho (スマホ, Sumaho, Smartphone) Fullbottle: Inserting this Fullbottle along with the Fullbottle Televi in the Twin Breaker, create a giant screen and launch smartphones.
• Robot (ロボット, Robotto) Fullbottle: Using this Fullbottle with the Sclashjelly Robot in the Twin Breaker, it makes a powerful finish.
  • Robot Sclashjelly: When using the Sclashjelly Robot in the Twin Breaker a powerful attack is made.
• Gatling (ガトリング, Gatoringu) Fullbottle: Using this Fullbottle in the Twin Breaker is able to throw a energy ball.
• Kuma (クマ, Bear) Fullbottle: Inserting this Fullbottle in the Sclash Driver is able to create a giant hands of kuma energy.
• Fukurou (フクロウ, Fukurō, Owl) Fullbottle: Using this Fullbottle with the Kuwagata Fullbottle in the Twin Breaker together with the Castle Fullbottle in the Sclash Driver, create a yellow with blue energy ball.
• Kuwagata (クワガタ, Kuwagata, Stag beetle) Fullbottle: Using this Fullbottle with the Fukurou Fullbottle in the Twin Breaker together with the Castle Fullbottle in the Sclash Driver, create a yellow with blue energy ball.
• Castle (キャッスル, Kyassuru) Fullbottle: Using this Fullbottle in the Sclash Driver together with the Fukurou and Kuwagata Fullbottle in the Twin Breaker, create a yellow with blue energy ball.

Kazumi Sawatari is portrayed by Kouhei Takeda (武田 航平, Takeda Kōhei).

Hokuto Three Crows

The Hokuto Three Crows (北都三羽ガラス, Hokuto Sanba Garasu) are a group of Hokuto soldiers who were originally workers of Kazumi Sawatari's farm and enlisted into Hokuto's military to repay their former employer's debt for financially supporting their families. Each are able to transform into enhanced form of the Smash known as Hard Smash (ハードスマッシュ, Hādo Sumasshu) and later the stronger Hazard Smash (ハザードスマッシュ, Hazādo Sumasshu), which gave increased strength but killed the user if they are knocked out of a transformation.

Akaba

Akaba (赤羽), real name Masaru Ooyama (大山 勝, Ōyama Masaru), uses the Castle (キャッスル, Kyassuru) Fullbottle to transform into the Castle Hard Smash (キャッスルハードスマッシュ, Kyassuru Hādo Sumasshu) that has the Catapulta Cannon (カタプルタキャノン, Katapuruta Kyanon) on his head and the two Ground Rampart (グランドランパート, Gurando Ranpāto) shields on his shoulder pads. He seems to possess a rather violent streak as shown in his initial appearance, where he attacks the civilian populations using his powers without any hesitation. When Seito began their assault on Touto in order to steal the Pandora Box, Akaba sacrificed his life to protect it from Gentoku.

Akaba is portrayed by Eishin (栄信).

Aoba

Aoba (青羽), real name Syuuya Aikawa (相河 修也, Aikawa Shūya), uses the Kuwagata (クワガタ, Kuwagata, Stag beetle) Fullbottle to transform into the stag beetle-themed Stag Hard Smash (スタッグハードスマッシュ, Sutaggu Hādo Sumasshu) that is armed with two sword-like Rapture Scissors (ラプチャーシザース, Rapuchā Shizāsu). Aoba is killed during the battle with Build and his newly acquired RabbitTank Hazard form, when the rampaging Build unintentionally uses the Hazard Finish against him. His death shocked both his own comrades and the Touto Riders, especially Sento who falls into depression over having taken a life.

Aoba is portrayed by Tateto Serizawa (芹澤 興人, Serizawa Tateto).

Kiba

Kiba (黄羽), real name Syoukichi Mihara (三原 聖吉, Mihara Shōkichi), uses the Fukurou (フクロウ, Fukurō, Owl) Fullbottle to transform into the Owl Hard Smash (オウルハードスマッシュ, Ōru Hādo Sumasshu) that has the two Forest Seeker (フォレストシーカー, Foresuto Shīkā) drones on his gauntlets. He has a childish behavior, even acting literally like a child throwing a fit when defeated by Build in one battle. After Aoba's death, he becomes bitter and more violent in combat. While trying to defend his homeland alone from Seito's invation, Kiba ended up becoming the Washio Brothers's hostage to force Kazumi into serving Seito. Despite Kazumi's effort to save him, Kiba is killed when he protected Kazumi from Remocon Bros' Funky Shot, dying in Kazumi's arms just as he said his farewell words to him.

Kiba is portrayed by Takuya Yoshimura (吉村 卓也, Yoshimura Takuya).

Prime Ministers

As a result of the Skywall Disaster (スカイウォールの惨劇, Sukaiwōru no Sangeki) in 2007, Japan has been divided into three different districts, namely Touto, Hokuto and Seito. It was suspected that everyone present at the event become much more aggressive after being exposed by the Skywall's Nebula Gas. As a result of the separation, several foreign powers have attempted to take advantage of the situation although neither of the districts display interest in allying with external forces.

Taizan Himuro

Taizan Himuro (氷室 泰山, Himuro Taizan) is the father of Gentoku and the Prime Minister of Touto (東都, Tōto). The country's system of governing and political goals are of traditional pacifism, only employing enough military strength for self-defense. Despite the rivalry between all three districts, Taizan wishes for Japan to reunite. Due to his poor health at the time of the unveiling of the Pandora Box, Taizan sent his son Gentoku in his behalf. Thanks to this, he was the only Prime Minister who was not affected by its radiation and managed to retain his sanity. During Faust's raid on Touto facility, Taizan ended up having a heart attack, and entrust his son to take care of Touto during his absence. However, unbeknownst to Taizan, his son is secretly one of Faust's high-rank member, Night Rogue. With Gentoku now in charge, Faust had managed to completely compromised the Touto government until Sento and Ryūga finally defeats Night Rogue, exposing his identity to Taizan who then orders his son to be taken into custody while apologizing to the Riders for the trouble Gentoku had caused them. Unfortunately, Sōichi later poisoned Taizan causing him to fall unconscious which once again gives Gentoku emergency power to rule Touto. He eventually recovered thanks to Misora's power and immediately exiled Gentoku for his actions while also looking for a way to end the war with the least bloodshed. Despite exiling Gentoku, Taizan still believe there still good in him and vow to return his son back to Touto.

At time when Namba and Stalk enacting their plan to bring humanity to chaos, Taizan is kidnapped by his son and held as a hostage by Stalk to force Sento reviving the original Project Build known as Project Evol, created by his father Shinobu in exchange for Taizan's life. However, it turns out that Gentoku was already planning to save his father, but despite Gentoku aiding the allied Kamen Riders to rescue Taizan and prevent Evolto from obtaining his Evol Driver and Evolbottles, the plan backfires, as Evolto retrieved his equipment to transform into Kamen Rider Evol. Taizan becomes the first victim of Evolto, sacrificing his life to save his son from the evil martian's deadly attack. However, this act of sacrifice allows Gentoku to fully revert back to his true self, redeeming Gentoku as he finally sides with the other Riders.

Taizan Himuro is portrayed by Meikyo Yamada (山田 明郷, Yamada Meikyō).

Yoshiko Tajimi

Yoshiko Tajimi (多治見 喜子, Tajimi Yoshiko) is the Prime Minister of Hokuto (北都), whose system of governing and political goals are based on social welfare, such as introducing childcare and agricultural programs, putting the needs of its people above all else. Unfortunately, the Skywall Disaster rendered most of its farmland infertile and the massive economic collapse forced many citizens to take their children out of school. Behind its people's backs, the government utilized most of their funds towards military strength, and Tajimi is revealed to have sinister motives regarding it. After Sōichi and Namba acquired the blueprints of Takumi's Project Build and Touto's guardians in order to manipulate the two other remaining region's Prime Minister into waging war and thanks to Gentoku's instigation that the other regions should just try and take the Pandora Box by force, she is the first one to declare war against Touto.

During Touto's decisive match against Hokuto, Tajimi acts on Sōichi's advise to station her entire military on Touto's border and invade the country on a contingency order should Grease be defeated. But this leaves Hokuto defenseless as Tajimi realizes too late that Faust manipulated her so her nation can be taken over by Seito while she is taken into their custody.

Yoshiko Tajimi is portrayed by Ryoko Gi (魏 涼子, Gi Ryōko).

Masakuni Midō

Masakuni Midō (御堂 正邦, Midō Masakuni) is the Prime Minister of Seito (西都), whose system of governing and political goals are based on economic recovery, doing so by sending its young adults across the world to gather technical knowledge. After Hokuto's declaration of war against Touto, Hokuto Prime Minister Tajimi offers him an alliance. While interested in the offer, he is ultimately revealed to be an opportunistic manipulator as he stood by sidelines to bide his time. When Hokuto lost the decisive match against Touto, Midō has the Seito military, led by the renegade Gentoku Himuro, in taking over the defenseless country and bringing Tajimi into their custody. But after losing the fight against Touto, Midō proves himself to be a man of his word as he refused to renege on the agreement he has made with Touto despite threats from Namba. For that, he was murdered by Sōichi. Namba then assumes his identity to use Seito a front for Namba Heavy Industries' operations and his future plots.

Masakuni Midō is portrayed by Norimasa Fuke (冨家 規政, Fuke Norimasa).

Namba Heavy Industries

Namba Heavy Industries Ltd (難波重工, Nanba Jūkō) is a company established by Jūzaburō Namba which provides financial support to Faust. Because of its massive influence, all three countries attempted of distancing themselves from the industry despite Namba having placed many agents within the governments' infrastructures. After Evolto murdered Seito's prime minister Midō so Namba can assume his identity, Namba Heavy Industries uses Seito's resources at its disposal to both launch a full scale invasion on Touto and construct the building known as Pandora Tower (パンドラタワー, Pandora Tawā) to utilize the Pandora Box and creating an empire named after their chairman.

Jūzaburō Namba

Jūzaburō Namba (難波 重三郎, Nanba Jūzaburō) is the corrupt and war-mongering chairman of Namba Heavy Industries. Initially appearing to be nothing more than a benefactor for Faust, collaborating with the organization and Evolto from Mars solely to acquire the Build system and use it for military applications, he has since become one of the main antagonists of the series, having been manipulating the three government regions as part of his agenda to use the Pandora Box's energy to create weapons surpassing the world's nuclear arsenal. He also brainwashed various children to serve as his personal army of infiltrators within the three governments, including Sawa Takigawa, although she has since cut all ties with him. A power-hungry man with a god-like complex, he is extremely ruthless and would not hesitate to sacrifice anything and anyone just to achieve what he wants.

After acquiring the Pandora Box while Hokuto and Seito served their purpose, Namba has Evolto murder Seito's prime minister Masakuni Midō to assume his identity. As a result, a new youthful Namba regains his mobility as his cover as Seito's prime minister in using the country's resources to begin the construction of Pandora Tower while launching a full scale invasion of Touto. His ultimate goal is to use the power of the Pandora Box to reform Japan, and eventually the entire world, under his own rule and in his own image. Although it is unknown if he is aware that Evolto is exploiting him for his own main goal of wiping out all life on Earth, Namba became wary of the alien and having aware enough of the Pandora Box's power to not open it willingly. He then panics when Evolto finally opens the Pandora Box, causing widespread damage as a result.

Jūzaburō Namba is portrayed by Akira Hamada (浜田 晃, Hamada Akira), while Norimasa Fuke portrays Namba's disguise as Masakuni Midō.

Namba Children

The Namba Children (難波チルドレン, Nanba Chirudoren) are scientists, soldiers, and spies who were brainwashed by Jūzaburō Namba to have complete loyalty to him since they were children. They are positioned as sleeper agents in the factions within Touto, Hokuto, and Seito to serve as Namba's eyes and ears while winning the trust of others to acquire whatever Namba needs.

Nariaki Utsumi

Nariaki Utsumi (内海 成彰, Nariaki Utsumi) is the 28-year old secretary of Himuro who was formally a Touto Institute scientist, little known about him and his personality other than being a Faust scientist who is highly loyal to Gentoku and is one of the Namba Children with his loyalty to Namba bordering on fanatism. But Utsumi expresses regret over his life choices, even commenting to Sento about their similar predicaments. He ends up masquerading as Night Rogue during Faust's plan to use Build and make it appear that the organization had been defeated. When Sento stopped him from committing suicide, Utsumi reveals his regrets and that he knew all along about Sento being Build. He falls into a river after being shot by Gentoku personally, with his last words to Sento being a warning for the latter not to end up like himself.

Assumed dead despite his body not found, Utsumi is later revealed to have been saved by Sōichi at the last second as he returns to Namba's side. Utsumi reveals himself to Gentoku during the Hokuto Invasion, although to what extent is still unknown as he did help Sento develop a self-destruct device for the Hazard Trigger. Utsumi later managed to obtain and perfected the Kaiser System which he gives to Seito for the Washio Brothers to use. During that time, he also showed a change in personality. Initially a reserved man who shows little emotions yet is remorseful, he has become a more open-minded and expressive sadist. Aiding Evolto on the assumption that it would benefit Namba, Utsumi ultimately learns of the alien's true plans as Namba urgently sends him to stop Evolto from opening the Pandora Box, only for the evil alien to casually blast Utsumi aside without even listening to a single word he said.

Despite not being a Faust leader, Utsumi uses his own Transteam Gun and a Bat Fullbottle to transform into his own Night Rogue form, serving as Gentoku's decoy and later on assisting Sento in gathering the Hazard Trigger's data. His version of Night Rogue grants him the ability to analyze his opponent through his visor. As the creator of the perfected Kaiser System, Utsumi is able to use it to transform into Hell Bros using the Nebula Steam Gun. As Hell Bros, his main weapon is the Nebula Steam Gun and the Steam Blade.

Nariaki Utsumi is portrayed by Yuki Ochi (越智 友己, Ochi Yūki). As a child, Utsumi is portrayed by Yusei Ohtake (大竹 優青, Ōtake Yūsei).

Masuzawa

Masuzawa (増沢) is a spy who works as the secretary to the Touto Prime Minister. When he is exposed by Sento, he committed suicide using a Fullbottle to avoid capture, he is responsible for putting a bug on the Dragon Fullbottle to spy on Sento and the others and pass on to Namba and Seito information about their plans

Masuzawa is portrayed by Taro Nakatani (中谷 太郎, Nakatani Tarō).

Washio Brothers

The Washio Brothers (鷲尾兄弟, Washio Kyōdai) are a pair of siblings from Seito who serve alongside Gentoku as Seito's main troopers. In the past they were part of the Namba Children, being trained since childhood by Jūzaburō Namba and brainwashed to swear allegiance only to him. They use the Kaiser System that was developed by Kaisei Mogami and later perfected by Nariaki Utsumi, with both using the Nebula Steam Gun (ネビュラスチームガン, Nebyura Suchīmu Gan) to transform.

Fū Washio

Fū Washio (鷲尾 風, Washio Fū) is Rai's older brother who uses the Gear Remocon (ギアリモコン, Gia Rimokon) to transform into Remocon Bros (リモコンブロス, Rimokon Burosu), a green-colored version of Kaiser. Although he primarily uses the Nebula Steam Gun in combat, Remocon can also utilize its Rifle Mode should Engine lend him the Steam Blade. He can also use his Gear Remocon with Rai's Gear Engine to transform into Hell Bros (ヘルブロス, Heru Burosu), an upgraded version of Bi-Kaiser. Personality-wise, Fū is calm and collected, but like his younger brother, is also a cruel sadist, taking enjoyment from other's suffering. He is also cunning, tricking Ryūga during their battle by claiming that his younger brother would be executed if he loses, causing the latter to hesitate and resulting in his victory. He then becomes confused and annoyed when Ryūga simply accepted his defeat instead of being provoked in response to his gloating.

Fū Washio is portrayed by Osamu Adachi (足立 理, Adachi Osamu). As a child, Fū is portrayed by Shinta Takaiwa (高岩 芯泰, Takaiwa Shinta).

Rai Washio

Rai Washio (鷲尾 雷, Washio Rai) is Fū's younger brother who uses the Gear Engine (ギアエンジン, Gia Enjin) to transform into Engine Bros (エンジンブロス, Enjin Burosu), a white-colored version of Kaiser Reverse. As Remocon is the primary user of Nebula Steam Gun, Engine utilizes the Steam Blade as his main weapon but can also utilize its Rifle Mode when Remocon lends him the Nebula Steam Gun. Unlike his older brother, Rai is more loud-mouthed and openly expresses disdain towards Gentoku, but like his brother, he is also a cruel sadist that enjoys tormenting others. He also uses dirty tactics in order to win, but they often backfire on him, such as when he collaborated with his older brother to lure Cross-Z into defeat only to be stunned by Ryūga not being provoked by his and his brother's gloating and later, during a battle with the Kamen Riders, he tried to use an unconscious Misora as a hostage and was instead sent flying by an energy burst when Vernage awakens inside her.

Rai Washio is portrayed by Yuudai Nasuda (奈須田 雄大, Nasuda Yūdai). As a child, Rai is portrayed by Taiga Watanabe (渡辺 虎雅, Watanabe Taiga).

Hard Guardians

The Hard Guardians (ハードガーディアン, Hādo Gādian) are enhanced versions of the Guardians which Namba Heavy Industries mass-produced in the wake of Seito's war declaration towards Touto. The Hard Guardians are equipped with a combat AI unit, right arm-mounted gatling-guns, left arm-mounted clawed gauntlets, and shoulder-mounted missile pods. Despite its heavy equipment, an improve drive module was placed on each joints to provide enhanced mobility. Depending on the situation, their equipment can be replaced per combat situations and is able to fight on equal terms against Rider Systems users.

Clone Smash

The Clone Smash (クローンスマッシュ, Kurōn Sumasshu) are cloned and enhanced versions of the Smash Hazard. Introduced in Episode 31, a Clone Smash is stronger and more resilient than its normal counterpart due to being unable to feel pain, although there appears to be a limit to this ability as in their debut episode, two were shown being affected by Cross-Z Magma's magma-based attacks despite easily shrugging off attacks from the other Riders earlier. They lack any form of intelligence, thus they would not stop fighting until they are destroyed

• The Press Clone Smash (プレスクローンスマッシュ, Puresu Kurōn Sumasshu) is a cloned and enhanced version of the Press Smash Hazard. It is easily destroyed along with the Stretch Clone Smash by Cross-Z Magma. The second Strong Clone Smash is destroyed along with the Flying Clone Smash by Grease.
• The Stretch Clone Smash (ストレッチクローンスマッシュ, Sutoretchi Kurōn Sumasshu) is a cloned and enhanced version of the Stretch Smash Hazard. It is easily destroyed along with the Press Clone Smash by Cross-Z Magma.
• The Strong Clone Smash (ストロングクローンスマッシュ, Sutorongu Kurōn Sumasshu) is a cloned and enhanced version of the Strong Smash Hazard. It is easily destroyed by Rogue.
• The Flying Clone Smash (フライングクローンスマッシュ, Furaingu Kurōn Sumasshu) is a cloned and enhanced version of the Flying Smash Hazard. It is destroyed along with the second Strong Clone Smash by Grease.

Mars civilization

Vernage

Vernage (ベルナージュ, Berunāju) is the former queen of Mars who survived the destruction of her civilization at the cost of her physical form. She manage to seal Evolto along with his Evol-Trigger into the Pandora Box, while separating his Evol Driver away to make sure he cannot use it inside the box to free himself. After Evolto possessed Sōichi brought the Pandora Box to Earth, her spirit was preserved in a bracelet which latched into a young Misora. 10 years later, Vernage's consciousness slowly awakened and occasionally rescuing the Kamen Riders from Namba's forces.

As her spirit resided within Misora's bracelet, she provided the young girl with the ability to purify Nebula Gas. The process came at the cost of displaying Vernage's memories of Mars' destruction within Misora's mind. Although presented as a powerful entity, she pointed out that her life force is running out as time passes on.

Vernage is voiced by Sora Amamiya (雨宮 天, Amamiya Sora).

Evolto

Evolto (エボルト, Eboruto) is an entity who manipulated the power of Pandora Box to destroy the Martian civilization and one of the main antagonists of the series. Shortly after destroying Mars, Evolto was sealed alongside his damaged Evol-Trigger within the Pandora Box by Vernage who made certain he did not have his Evol Driver to escape his prison from inside. Ten years prior to the series, he possess the body of Sōichi Isurugi when the man found the Pandora Box and the Evol Driver, completely suppressing his host. Twenty three years ago before possessing Soichi, Evolto would learn that he only possessed half of his full power as the rest was within Pandora Box, which later resided in Ryuga since his birth through his mother Yuri accidentally making contact with the sealed energy of Evolto, and his half lost his memories at time of Ryuga's birth. A cruel and ruthless character, Evolto committed several heinous acts using Sōichi's body as a vessel, killing without hesitation, manipulating Sōichi's daughter for his plots and even turned a child into a Smash on one occasion. Via Sōichi, Evolto could transform into Blood Stalk before finally becoming Kamen Rider Evol (仮面ライダーエボル, Kamen Raidā Eboru), eventually transferring himself to Ryūga's body to regain his full power and then into Sento so he can use his IQ to repair the Evol-Trigger. According to Vernage, Evolto would have the power to wipe out the known universe should he use the restored Evol-Trigger while in his final Phase 4 form.

While possessing Sōichi, Evolto masterminded framing Shinobu for the Skywall Disaster, faking an amnesiac Takumi Katsuragi's death while switching his appearance with that Tarō Satō while naming him "Sento Kiryū" to use in perfecting the Build System. Evolto also manipulated Ryūga's life, a having implanted his genetic code in the human's DNA to prepare him as his ideal vessel which he eventually transferred himself into. Ultimately, Evolto plans on using the Pandora Box to destroy Earth's civilizations, exploiting Namba as they engineered a series of schemes to take over Hokuto and Seito with only Touto and its Kamen Riders as their opposition.

Despite his manipulations and preparations, however, Evolto himself is not immune to unexpected occurrences. This was shown when he expressed mild surprise and annoyance that Vernage was still alive, although he took pleasure in noting that Vernage's life force was fading, and later when he discovers that Sento has disabled the killer chip implanted in Gentoku, allowing the latter to ally himself with Sento and the other Riders without risk of being killed, which messes up Evolto's plans and caused him to become enraged for the first time in the series.

Evolto becomes Kamen Rider Evol, using the Evol Driver (エボルドライバー, Eboru Doraibā) and Evolbottles (エボルボトル, Eborubotoru) which was Build System was reversed engineered from. Evolto's finishing move is the Evoltic Finish (エボルテックフィニッシュ, Eborutekku Finisshu).

• Rider (ライダー, Raidā) Evolbottle: Used by Evol to access his basic forms.
• Cobra (コブラ, Kobura) Evolbottle: A Evolbottle version of Sōichi's Fullbottle that Evol uses in combination with the Rider Evolbottle to access his Phase 1 Cobra Form.
• Dragon (ドラゴン, Doragon) Evolbottle: A Evolbottle version of Ryūga's Fullbottle that Evol uses in combination with the Rider Evolbottle to access his Phase 2 Dragon Form. In this form, achieved by possessing Ryūga's body, Evol uses Cross-Z's Beat Closer as his weapon.
• Rabbit (ラビット, Rabitto) Evolbottle: A Evolbottle version of Sento's Fullbottle that Evol uses in combination with the Rider Evolbottle to access his Phase 3 Rabbit Form. In this form, achieved by possessing Sento's body, Evol uses Build's Drill Crusher as his weapon.
• Unidentified Phase 4 form: According to Vernage, this form is Evol's most dangerous final phase that has a potential to destroy the entire universe. This form can only be accessed with Evol-Trigger (エボルトリガー, Eboru-Torigā), which the Hazard Trigger was reverse-engineered from. Having been damaged prior to being sealed in the Pandora Box, Evolto possesses Sento to use his intelligence to repair the Evol-Trigger

Evolto is voiced by Tetsuo Kanao (金尾 哲夫, Kanao Tetsuo).

Faust

Faust (ファウスト, Fausuto) is a mysterious terrorist organization who conduct experiments on humans to create the Smash creatures. It was originally founded by Touto's former scientist Takumi Katsuragi and Gentoku Himuro. They are in possession of one of the Pandora Box's panels that was split during the Skywall Disaster, along with Nebula Gas they extracted from the Skywall and liquefied into the element used in the development of Fullbottles. According to Gentoku, who took over the organization when Takumi was disposed by Evolto possessed Sōichi, Faust's objectives are to achieve Takumi's goals of evolving humanity into the "Ultimate Lifeform" via Nebula Gas. Despite its questionable methods, Faust's goals were originally meant for the betterment of Touto until Gentoku learned too late that the organization was compromised by Evolto and Namba whose goal is to reassemble the Pandora Box and repeat the calamity that destroyed the ancient Martian civilization.

Since they were formed in Touto, Faust members have infiltrated the Touto Institute of Advanced Matter Physics (東都先端物質学研究所, Tōto Sentan Busshitsugaku Kenkyūjo), which has been studying the Pandora Box ever since the Skywall Disaster while also preventing it from being stolen by neighboring countries. Despite their public image as peacekeepers and their own pacifist ideals, Faust's influence has caused the Touto Institute to mass-produce weapons while not hesitating in using lethal force when pursuing convicts. During Gentoku's temporary takeover as the Prime Minister, Faust had relocated from Touto and manipulated the two other nations into a war to acquire the rest the Pandora Box. Hokuto and Seito served their purpose as the Pandora Box is eventually reassembled with Faust and Namba finally enacting their scheme to devastate Earth.

Leaders

The Faust's acting leaders utilized the Transteam System (トランスチームシステム, Toransuchīmu Shisutemu), which Takumi Katsuragi reverse-engineered from Kaisei Mogami's Kaiser System, that requires organic Fullbottles to transform with their identities concealed by built-in voice changers in their armor. Their main weapons are the Transteam Gun (トランスチームガン, Toransuchīmu Gan), which allows them to perform the Steam Break (スチームブレイク, Suchīmu Bureiku) and Steam Attack (スチームアタック, Suchīmu Atakku) finishing moves, and the Steam Blade (スチームブレード, Suchīmu Burēdo), which allows them to initiate the Elek Steam (エレキスチーム, Ereki Suchīmu), Ice Steam (アイススチーム, Aisu Suchīmu) and Devil Steam (デビルスチーム, Debiru Suchīmu) special attacks. Each of the leaders can also combine their weapons into the Steam Rifle (スチームライフル, Suchīmu Raifuru), which allows them to perform one of two finishing moves: Steam Shot (スチームショット, Suchīmu Shotto) or Steam Attack.

Gentoku Himuro

Gentoku Himuro (氷室 幻徳, Himuro Gentoku) is the 35-year old Special Advisor to his father Prime Minister Taizan Himuro and head of the Touto Institute. Before being exposed to the Pandora Box's radiation, Gentoku was a kind and rather laid-back person who had the country's best interest in mind, although he disagreed with his father's pacifistic methods. The Pandora Box changed Gentoku into an aggressive, greedy and paranoid man, although unlike the others affected by the Pandora Box, Gentoku's personality changes were not immediate, as he once tried to convince Takumi Katsuragi to abandon his human experiments shortly after they created Faust, only to continue these experiments himself once the changes became complete. He generally hides his new personality well in public, appearing as a level-headed official, with no one suspecting his true identity as one of Faust's founding member Night Rogue (ナイトローグ, Naito Rōgu). Despite his sadistic tendencies towards his victims' suffering, Gentoku displays concern for both his father and nation, but the effects of the Pandora Box made him willing to use extreme methods for their sake.

Initially unaware of Sōichi's actions of turning Takumi into Sento, overseeing the experimentation on the youth, Gentoku manipulates Sento into perfecting the Build system so he can later take the technology to fortify Touto's military strength while attempting to prevent Sento from regaining his memories. But this puts Gentoku at odds with Sōichi, which worsens when Gentoku becomes acting prime minister when Taizan suffered a heart attack during Faust's successful raid on the Touto Institute. It results with Sōichi exposing Gentoku as Night Rogue to the public, with Gentoku abandoned by Faust as he was briefly arrested. Gentoku responds to the treachery by revealing Sento's true identity as Takumi Katsuragi and Sōichi's position in Faust.

After Taizan was poisoned by Sōichi, Gentoku reassumes the role of acting Prime Minister while recruiting Sento and Ryūga to aid the Touto military when Hokuto declared war. But when Gentoku attempts to send Ryūga on a mission to attack a defenseless Hokuto, he was dismissed by a recovered Taizan and sentenced to exile. Gentoku refuses to accept this and attempts to steal the Pandora Box, only to be driven off by Build RabbitTank Sparkling while vowing revenge against all of Touto. Gentoku later accepted Sōichi's offer of turning him into the strongest Rider and is subjected to a series of experiments to increase his hazard level so he can use a Sclash Driver, the process rendering him a near-emotionless nihilist. Allying himself with Seito to lead its army as Kamen Rider Rogue (仮面ライダーローグ, Kamen Raidā Rōgu), he is now hellbent on destroying Touto and reuniting Japan. However, he soon finds himself questioning Namba's intentions, which conflicts with his own current ideologies. This prompted him to reveal to the other Riders during a battle with them the truth behind Kasumi Ogura's sacrifice: It was actually part of Stalk's plan to lure Ryūga into unleashing his birth Hazard Martian gene in endless combat. He also reveals that Namba was disguised as the late-Seito Prime Minister Mido, and that Namba had implanted a chip in his body that would kill him should he betray them, which is why he waited until he was out of Namba's sights to admit everything before he allowed Sento to knock him out, yet this still failed to destroy the chip in him.

Ever since being defeated by Build during the 2-out-of-3 match between Seito and Touto, Gentoku has begun to show signs of regaining his humanity and conscience, which is later revealed by Evolto to be the result of Gentoku's transition into a Kamen Rider restoring his original personality. However, Gentoku believed he was beyond redemption due to everything that he had done, decided to continue playing the villain so his father can unify the country until, in a desperate attempt to save his father, breaks down and calls Sento for help, with Sento changing the chip's signal frequency upon realizing Gentoku's emotions were genuine, rendering it useless. After Taizan sacrifices himself to save his life, Gentoku, encouraged by his father's last words, finally begins to seek redemption by allying himself with the other Riders against Evolto and Namba.

Gentoku uses the Bat (バット, Batto) Fullbottle to transform into Night Rogue. Aside from being a skilled combatant, he can manipulate steams from his body for quick travel and summoning electrical energy to create an energy punch. Through his animal motif, he is capable of clinging to ceilings and summon a pair of bat wings from his back, allowing him to swoop about at high speeds while performing powerful dive-bomb attacks.

As Kamen Rider Rogue, uses Crocodile Crack Fullbottle (クロコダイルクラックフルボトル, Kurokodairu Kurakku Furubotoru) and the Sclash Driver to transform. Having strength that rivals even Build's Hazard forms, he is armed with the Nebula Steam Gun (ネビュラスチームガン, Nebyura Suchīmu Gan). Using the Sclash Driver, Rogue can initiate the Crack Up Finish (クラックアップフィニッシュ, Kurakku Appu Finisshu) finisher attack. Using the Nebula Steam Gun, he can initiate two finishers, the Funky Break (ファンキーブレイク, Fankī Bureiku) in its gun form or the Funky Shot (ファンキーショット, Fankī Shotto) in its rifle form.

• Phoenix (フェニックス, Fenikkusu) Fullbottle: Inserting this Fullbottle in the Nebula Steam Gun can become a phoenix of pure flame.
• Diamond (ダイヤモンド, Daiyamondo) Fullbottle: Inserting this Fullbottle in the Sclash Driver create small diamonds to attack and also purple shields of diamonds.

Gentoku Himuro is portrayed by Kensei Mikami (水上 剣星, Mikami Kensei).

Sōichi Isurugi

Sōichi Isurugi (石動 惣一, Isurugi Sōichi) is the rather enigmatic 48-year old owner of nascita and Misora's father who is actually Faust's high-ranking member Blood Stalk (ブラッドスターク, Buraddo Sutāku). He is a kind-hearted man and a good friend to Takumi's father Shinobu Katsuragi. Ten years prior to the series, he was the astronaut who discovered the abandoned Evolt Driver, and eventually the Pandora Box on Mars, resulting with him being possessed by the evil entity Evolto who subjugated his mind while using the man's body to commit numerous atrocities from causing the Skywall Disaster by coming in contact with the Pandora Box to frame Shinobu, manipulating Takumi's current identity Sento and Sōichi's daughter Misora for his own ends. But Sōichi's personality resurfaces on occasion, having briefly surfaced in an attempt to fight Evolto before being suppressed. He was later tricked by Evolto into thinking that the alien would leave his body upon retrieving the Evol Driver. Following Evolto having transferred himself into Ryuga's body, Sōichi is finally freed, but unfortunately, also left in a coma. He is now currently hospitalized under Sawa's care.

Due to being possessed by Evolto, Sōichi gains several inhuman abilities. He can transmute matter, as shown when he transformed his tablet computer into pieces of paper. He can also mold a person's face into that of another person while also manipulating their memories, he is also able to return his original face to a person once he changes it. He is also shown to be capable of quickly leaping into the air to escape.

With Evolto possessing him, Sōichi uses the Cobra (コブラ, Kobura) Fullbottle to transform into Blood Stalk. As Blood Stalk, he is a skilled fighter who can poison his opponents by stabbing them with an appendage, as well as hack several of Touto's Guardians at once into following his orders. Through his animal motif, he can summon a projection of a large cobra for various applications. With the Devil Steam, he is able to either release Nebula Gas to change regular people into Smash via the Steam Blade or inject a Smash with a Nebula Gas-filled bullet to enlarge them into giants via the Steam Rifle.

• Rocket (ロケット, Roketto) Fullbottle: Inserting this Fullbottle into the Steam Nebula can launch an energy rocket.

Sōichi Isurugi is portrayed by Yasuyuki Maekawa (前川 泰之, Maekawa Yasuyuki).

Faust agents

Masahiro Nabeshima

Masahiro Nabeshima (鍋島 正弘, Nabeshima Masahiro) is a prison guard who is blackmailed by one of Faust's agents, Blood Stalk/Sōichi, by threatening his family to arrange for Ryūga Banjō to be sent to the prison he works at after framing him with the death of Touto Institute researcher Takumi Katsuragi. He then abducted Ryūga and bring him to Faust for experimentation. After luring Sento and Ryūga to Seito per Night Rogue's orders, he was converted into Mirage Smash as a "reward" and later on into Square Smash as part of Blood Stalk's experiment. Although rescued by Build and Ryūga, the effect of being converted into a Smash twice erased almost all of his memories to the point of forgetting his own family members. His last fragment of memory was the recognition of how both Faust and Sōichi came into possession of the Pandora Box's panels. Sometime later, he regains all his memories and calls Sento to reveal more information about Faust as a debt of gratitude for saving his life. As Nabeshima realize that there are too many undercover Faust agents around Touto, Nabeshima calls Sento privately to reveal Sōichi's identity as Blood Stalk and his involvement with framing Ryūga for supposedly murdering Takumi. He and his family later are captured by Nanba's forces and used as leverage against Sawa to force her to betray her friends, but Sawa then sends Kazumi to rescue them.

• Mirage Smash (ミラージュスマッシュ, Mirāju Sumasshu): Nabeshima's swordsman/ninja-themed first transformation. He is armed with two sword-like Slismashers (スライスマッシャー, Suraisumasshā) and can create illusions of himself from the two lantern-like Mirage Summoners (ミラージュサモナー, Mirāju Samonā) on his shoulder pads. While engaging in a fight against Build at a Touto pier, Build countered and defeated him via the Hawk Gatlinger. His Smash essence was collected and purified to make the Ninjya Fullbottle.
• Square Smash (スクエアスマッシュ, Sukuea Sumasshu): Nabeshia's cube/comic panel-themed second transformation upon his kidnapping by Blood Stalk. He is armed with a built-in pen-like blade on his right arm called the Area Cut Pen (エリアカットペン, Eria Katto Pen), which can create portals to sneak attack from behind, slice through large buildings with a single cut and create blocks from various materials. He was used by Blood Stalk to lure Build and was enlarged by Stalk using the Devil Steam before being defeated by Build HawkGatling Form. His Smash essence was collected and purified to make the Comic Fullbottle.

Masahiro Nabeshima is portrayed by Ichi Omiya (市オオミヤ, Ichi Ōmiya).

Eita Kawai

Eita Kawai (河合 栄多, Kawai Eita) is a researcher in the Touto Institute who is one of Katsuragi's sympathizers. He successfully uploaded the full data of Pandora Box before the Faust army led by Stalk raids on Touto Institute to steal the box. He is transformed into the Press Smash Hazard (プレススマッシュハザード, Puresu Sumasshu Hazādo) by Blood Stalk to handle Ryūga Banjō, but was easily defeated by Ryūga. A weakened Kawai was reverted back to his human form by Stalk. After returning to his human form, he tells Stalk that he believe he is actually the still alive Takumi Katsuragi, but Stalk denies it and proceed to erase Kawai's memories and turned Kawai's face into Kuwata's in front of Sento, which gives Sento another clue about Stalk's possible connection with Takumi's faked death.

Eita Kawai is portrayed by Tsukasa Honjo (本庄 司, Honjō Tsukasa).

Shingo Kuwata

Shingo Kuwata (桑田 真吾, Kuwata Shingo) is a researcher in the Touto Institute who is one of Katsuragi's sympathizers. He uses his Fullbottle to become his own version of the Flying Smash. After being defeated by Build LionCleaner Form, he reveals that he was merely bait to successfully lure Build away from interfering in Faust's raid on the Touto Institute and steal the Pandora Box. Before committing suicide via his own Fullbottle, he reveals to Build that Takumi is still alive and had been faking his death all along.

Shingo Kuwata is portrayed by Ryo Yoshida (吉田 亮, Yoshida Ryō).

Guardians

The Guardians (ガーディアン, Gādian) are enforcement androids mass-produced by Namba Industries as peacekeepers of each countries. At first, only Touto is seemingly able to build Guardians, until the revelation that Namba has been supporting the other two Governments as well. They also act as sleeper agents of Faust and their true programming can be activated by Blood Stalk.

They are armed with the Safeguard Rifles (セーフガードライフル, Sēfugādo Raifuru) and ride motorcycles called Capital Roaders (キャピタルローダー, Kyapitaru Rōdā). A large number of them can combine together to form a single gigantic robot equipped with multiple guns. Under Faust's servitude, the removal of safety panels allows the reprogramed Guardians to act as suicide bombers if needed.

Smash

The Smash (スマッシュ, Sumasshu) are monsters who were originally humans that have been injected with the liquefied Nebula Gas as part of Faust's experiments. This process results in the experimented losing almost every remaining memories of the victims have left. In order to revert a Smash back to a normal human, the Kamen Riders must defeat them and extract their element liquids into an Empty Bottle which can then be purified into a Fullbottle for their transformation and equipment uses. Faust agents are given their own Fullbottles to transform into their Smash forms, which are equipped with a self-destruct function for the users in order to avoid capture. The true plan behind the experiment was to find a perfect candidate for the use of the Build Driver, with the Smash transformations labelled as failures. Each victim is ranked by their tolerance of Nebula Gas called Hazard Levels (ハザードレベル, Hazādo Reberu).

• Hazard Level 1: Patients with frail body types, thus making any attempt to revert these particular type of Smash back to their original human form impossible, leaving Build no choice but to kill the victimized Smash and end their suffering.
• Hazard Level 2: Patients with the ability to survive the gas and transform into Smash. Those who rank above 2 can retain their human forms (with one example being Ryūga) and were given the chance to raise their Hazard Levels through fighting experiences.
• Hazard Level 3: Patients who completed their tolerance towards the gas. They are also considered suitable candidates for the Build Driver.
• Hazard Level 4: Compatible users of Sclash Drivers. Patients in level 3 can also reach this level by using the Build Driver combined with the Hazard Trigger.
• Hazard Level 5: A level which can only be accessed by Evolto's race. This is required to access Evol-Driver.
• Hazard Level 6: The limit of a human body which was obtained by Build when he taps into the power of a Pandora Box's panel.

The Smash monster includes:

• The Needle Smash (ニードルスマッシュ, Nīdoru Sumasshu) is a needle/hedgehog-themed Smash that can use his sharp, neurotoxins-filled fingernails, his arm blades, and his stretched back full of needles to attack. He is quickly defeated by Build, who extracts the Needle Smash's element liquid to refine into the Harinezumi Fullbottle.
• The Strong Smash (ストロングスマッシュ, Sutorongu Sumasshu) is a rock/gorilla-themed Smash who uses his bare hands to fight, wields vast physical strength, and has the ability to greatly jump very high. He was originally Shimizu (志水), who was present during Ryūga's escape from Faust's experiment on getting rid of his memories and was turned into the Strong Smash to retrieve him following his successful escape. He is defeated by Build who extracted the element liquid from him, restoring Shimizu in the process despite his memory loss. The Strong Smash's element is later purified to make the Gorilla Fullbottle. Shimizu is portrayed by Shohei Yamazaki (山﨑 将平, Yamazaki Shōhei).
• The Burn Smash (バーンスマッシュ, Bān Sumasshu) is a fire/dragon-themed Smash armed with the flamethrower-like Smash Burner (スマッシュバーナー, Sumasshu Bānā) on her right arm. She was originally Kasumi Ogura (小倉 香澄, Ogura Kasumi), Ryūga's girlfriend who was tricked by Nabeshima to send Ryūga to the scene of Katsuragi's death. After Ryūga was escaped Faust with Sento's help, the organization kidnapped her and converted her into a Smash while brainwashing her. Sent to hunt down Ryūga, her original persona surfaces as she fights her programming at risk to herself. As Kasumi's illness made it impossible for her to regain her humanity, Build is forced to destroy her while delaying his deathblow long enough for her to share her last words with Ryūga and reveal vital information about Faust. The Burn Smash's element is later purified to make the Dragon Fullbottle which Sento gives to Ryūga. Sometime later, Sento gave Ryūga her will, providing him with the resolve to fight as Kamen Rider Cross-Z. As revealed by Gentoku, the former Night Rogue now Kamen Rider Rogue, Kasumi's sacrifice was actually a set-up by Stalk from beginning, in attempt to unleashed Ryūga's birth Hazard martian genes through endless combats. Kasumi Ogura is portrayed by Risako Itō (伊藤 梨沙子, Itō Risako).
• The Flying Smash (フライングスマッシュ, Furaingu Sumasshu) is a scarecrow/hawk-themed Smash that can fly by controlling the surrounding air current and attack using her Air Slash Claws (エアスラッシュクロー, Ea Surasshu Kurō) to attack at high-speeds from the air. She was originally Reika Kine (木根 礼香, Kine Reika), mother to Kōta Kine (木根 光多, Kine Kōta). After being turned back to human, she returns with her son to help Sawa and Ryūga alongside boatman Igarashi (五十嵐) who operates a boat she and her husband owns. The Flying Smash's element is later purified to make the Taka Fullbottle. Reika Kine is portrayed by Machiko Kochi (東風 万智子, Kochi Machiko).
• The Press Smash (プレススマッシュ, Puresu Sumasshu) is a machine press-themed Smash with powerful pressing mechanisms in each part of his body to attack and destroy enemies by compressing his arms. He was originally Tatsuya Kishida (岸田 立弥, Kishida Tatsuya), an old friend of Tarō Satō since middle school with whom he formed a musical band called Lynks and believes Sento to be Tarō. While walking alone at night, Tatsuya is kidnapped by Blood Stalk and turned into the Press Smash to lure Sento out. Despite being returned to normal by Build NinninComic Form, Ryūga later knocks Sento out and reverts Tatsuya back to his Smash form in order to use him to find Faust's secret location. His Smash form's Hazard Level has been increased to cause his body to go haywire and about to be destroyed, until Build NinninComic Form saved him during his and Ryūga's raid on Faust's secret lab. Tatsuya later revealed he was present on September 9th, the day Takumi Katsuragi died, when he was dropping Tarō off to Katsuragi's apartment, another foreshadowing of Sento's real identity. The Press Smash's element is later purified to make the Panda Fullbottle. Tatsuya Kishida is portrayed by Pinboke Tarō (ピンボケたろう).
• The Ice Smash (アイススマッシュ, Aisu Sumasshu) is a Smash that can shoot Icicle Chill Arrows (アイシクルチルアロー, Aishikuru Chiru Arō). He was originally Takehiko (雄彦), a boy living in Hokuto who was transformed by Blood Stalk via the Steam Blade's Devil Steam. He is shortly purified by Build, although the stress from transforming into a Smash put a huge toll on his body. The Ice Smash's element is later purified to make the Shoubousha Fullbottle. Takehiko is portrayed by Sasuke Sasaoka (笹岡 サスケ, Sasaoka Sasuke).
• The Strong Smash Hazard (ストロングスマッシュハザード, Sutorongu Sumasshu Hazādo) are enhanced versions of the Strong Smash. The first Strong Smash Hazard the Kamen Riders encountered was originally Takumi's mother Kyōka Katsuragi (葛城 京香, Katsuragi Kyōka) who was abducted from Hokuto and transformed by Faust until she was purified by Build FireHedgehog Form with the extracted element purified to create the Lock Fullbottle. The second Strong Smash Hazard is a Touto soldier that Gentoku personally transformed and is later defeated by Cross-Z. The third Strong Smash Hazard was sent by Hokuto to attack Touto before being easily defeated by Kazumi. Kyōka Katsuragi is portrayed by Hiro Komura (古村 比呂, Komura Hiro).
• The Stretch Smash Hazard (ストレッチスマッシュハザード, Sutoretchi Sumasshu Hazādo) is an enhanced version of the Stretch Smash. It was created by Gentoku to fight the Kamen Riders using one of two unnamed Touto soldiers after he reveals his identity as Night Rogue in front of them. It targeted Misora who was caught in the battle and knocked her out before being defeated and restored back to human by Build and Cross-Z combining their finishers.
• The Flying Smash Hazard (フライングスマッシュハザード, Furaingu Sumasshu Hazādo) is an enhanced version of the Flying Smash. It was sent by Hokuto to attack Touto. It was defeated by Build and Cross-Z before being turned back to human.
• Another Press Smash Hazard was sent by Hokuto to attack Touto. It was defeated by Build before being turned back to human.

Kaisei Mogami

Kaisei Mogami (最上 魁星, Mogami Kaisei) is the main antagonist of Kamen Rider Heisei Generations Final: Build & Ex-Aid with Legend Rider. A cyborg, Mogami was a researcher in the Touto Institute of Advanced Matter Physics and an associate of Takumi Katsuragi. Ten years ago, while researching parallel universes, he found the Bugster Virus at the Skywall before concluding that the virus is from a parallel universe. He wanted to create the interdimensional gateway Enigma (エニグマ, Eniguma), but couldn't get research money for it so he moved to Namba Heavy Industries to continue his research. With Takumi's help, he developed both the Kaiser system and the Enigma which allowed him to make contact with a prime universe version of himself who is a Foundation X scientist. However, he lost the left side of his body due to an Enigma accident, caused by Takumi who opposed his ultimate goal. He resurfaces to cause the fusion and destruction of the two universes using the Enigma in order to fuse with his counterpart into a single immortal entity and become the ruler of all the universes. The two Kaiseis form an alliance as they employ Foundation X's own version of the Guardians known as the X Guardians (Xガーディアン, Ekkusu Gādian) while creating the Nebula Bugster strain.

Mogami is able to transform into the blue-colored Kaiser (カイザー, Kaizā), while his counterpart transforms into the red-colored Kaiser Reverse (カイザーリバース, Kaizā Ribāsu). They can also combine to form a single entity known as Bi-Kaiser (バイカイザー, Bai Kaizā).

Despite being defeated by Build and Ex-Aid, Nariaki managed to get Kaisei's Kaiser Project blueprints, which he later perfected and gave to Seito for their own use. The blueprints are later adapted into the Hell Bros gear, which is used by the Washio brothers.

Kaisei Mogami is portrayed by Kenji Ohtsuki (大槻 ケンヂ, Ōtsuki Kenji).

External links

• Cast on TV Asahi