Universe of Kingdom Hearts
The Kingdom Hearts video game series, developed by Square Enix in collaboration with Disney, takes place in the Disney universe with numerous self-contained worlds based on intellectual properties from both companies. Many of these worlds are based on animated Disney movies, though Kingdom Hearts II introduced worlds based on live-action Disney films as well. In addition to the Disney worlds, a number of original worlds appear over the course of the series. The series centers around the main character Sora's search for his friends and his encounters with Disney and Final Fantasy characters on their worlds. The first game, Kingdom Hearts, takes him through each world to lock their keyholes and prevent the Heartless from destroying them. The sequel Kingdom Hearts: Chain of Memories takes place in Castle Oblivion, where he visits memory-based simulations of many of these worlds that are generated on-the-fly as he travels through them. In Kingdom Hearts II, Sora helps the residents of these worlds again in search of his friend Riku. The Kingdom Hearts games have been both critically acclaimed and commercially successful and the design of the worlds has been praised for its faithfulness to the source material.
Concept and design
The Kingdom Hearts games are divided into various game levels, referred to as "worlds", which the player progresses through over the course of each game. Worlds vary in appearance, typically dependent on the Disney setting which they are based on. The worlds' graphics resemble the art style from the originating Disney film and the worlds are inhabited by characters from their respective films; for example, Hercules and Philoctetes appear in Olympus Coliseum from Hercules, while Aladdin, Princess Jasmine, and the Genie appear in Agrabah from Aladdin. The game worlds consist of interconnected field maps where battles and plot-related events occur. Players travel from one world to another via a Gummi Ship, or in Kingdom Hearts Birth By Sleep, characters travel via "keyblade glider". In 358/2 Days, Corridors of Darkness are used. In Dream Drop Distance, "Sleeping Keyholes" and "portals" are used. Worlds created specifically for the game mirror the overall appearance of the other worlds and predominantly feature characters from Final Fantasy games and original characters.
Though Disney gave director Tetsuya Nomura freedom to choose which characters and worlds would be used in the games, he and his staff tried to stay within the established roles of characters and boundaries of the worlds. Nomura found managing and keeping consistent multiple worlds to be problematic. After determining the number of worlds in the universe, Nomura picked ones he felt would fit into the series' scenario. The list was then evaluated by his team and finally by Disney representatives. Nomura tried to maintain the same number of worlds in each game and made an effort to minimize any overlap in the overall look and feel of each world. He and his staff accomplished this by categorizing various Disney worlds by appearance and setting. For example, a world based on The Jungle Book was considered for the first game, but was omitted due to its similarity to Deep Jungle from Tarzan. They also tried to take into account worlds with Disney characters that would be interesting. For example, Nomura chose to include a Mulan world for its unique atmosphere. The Tron world's design was meant to emulate an old computer game. Nomura got the idea to include this world after seeing a Disney employee working on Tron 2.0. He hoped that the fact that it was so different from the other worlds would make it enjoyable to players.
Common elements and basic concepts
Nomura intended hearts as well as the strengths and connections of the heart to be a common theme in the games. Characters within the Kingdom Hearts series are composed of three parts: body, soul, and heart. The body acts as a vessel for the heart and soul, with the soul giving life to the body. The heart holds their memories, and gives them emotion, light, and darkness. The soul is the least focused on in the series, everything relates back to the heart. When darkness consumes a character's heart, they become corrupted and turn into Heartless; a Nobody is created from the remaining body, which is considered to be the "empty shell" that the heart once inhabited, when the victim is of strong heart and will; the "empty shell" is what's left behind. Heartless act as forces of darkness, seeking to consume more hearts, including those of worlds. In addition, it still appears that people can "die" like normal if not transformed into a Heartless. Disney's Hades rules over the afterlife—or, more accurately, the underworld—where the deceased of various worlds seem to end up, including Auron from Final Fantasy X.
The Kingdom Hearts universe is divided into planes of existence called "realms". Most of the series takes place in the "realm of light". Opposite the realm of light is the "realm of darkness", where Kingdom Hearts resides and where Heartless are born. The "in-between realm" is a plane where Nobodies come into existence. As well as these known realms, Ansem the Wise was banished to a "realm of nothingness", which he described as a realm "where all existence has been disintegrated".
Heartless and Nobodies
The Heartless (ハートレス Hātoresu?) are hearts corrupted by darkness, lacking a body or soul. They are named "Heartless" for their total lack of emotional capacity and are the most common type of enemy the player encounters in the Kingdom Hearts games. Originally there are only "Pureblood" Heartless, black shadow creatures that lack hearts who were born of pure darkness, and usually exist in the realm of darkness, rarely appearing in realm of light. However, the experiments by Ansem the Wise and his apprentices into the capacity of the heart lead to the seemingly unintentional creation of Heartless in the Realm of light.
While researching these Pureblood Heartless, a side effect of their research to control the mind through the heart, Xehanort and Ansem's other apprentices devise the means to create artificial "Emblem" Heartless via the corruption of living hearts. Unlike Purebloods, which dissolve into black smoke when defeated, Emblem Heartless release hearts once defeated. However, unless the Keyblade is used to defeat the Heartless, the stolen hearts go to the realm of darkness where they turn into Heartless again. Ordinarily, the Heartless are mindless and function on instinct, but obey those with strong will. However, in worlds closer to darkness, the Heartless are stronger and become uncontrollable. They invade worlds through corridors of darkness, which are unpredictable pathways that interlink the many worlds.
When Heartless are created, the body and soul of those with strong hearts that have lost their hearts to darkness may become another type of creature called a Nobody (ノーバディ Nōbadi?). As they lack hearts possessing light and darkness, they are "nothing", yet still exist within the Kingdom Hearts universe. Members of Organization XIII, a group of Nobodies central to the plot of the series, keep their human form because they possessed strong hearts as humans and thus remember their original existence. However, if they lack memories, such as weaker Nobodies, they assume malformed, inhuman shapes. Most members of the Organization control one type of Nobody suited to their fighting style. It's interesting to note that Roxas lacked any conscious memories from his time as Sora, but retained a human form; it's likely thanks to the strength of Sora's heart (Or the presence of Ventus in Sora).
Like the Emblem Heartless, Organization XIII and the Nobodies have an insignia—an upside-down, incomplete heart—which was designed to look like a splintered heart as a complement to the Heartless emblem. However, upon being defeated, a Nobody fades into a state of non-existence until its Heartless counterpart is destroyed with the captive heart released, recreating the original being they were splintered from. However, though many start off as emotionless beings, Nobodies eventually develop a heart over time and become complete beings again. Despite this, they can still fade into a state of non-existence and reunite with their original heart, as seen in Axel's case. In the case of Roxas, unlike those who look nearly identical to their original selves, his form was a reflection of Ventus, though considered Sora's Nobody.
Namine is also a special case, being Kairi's Nobody, though lacking her body and soul, having been born with Roxas from Sora when he used the Keyblade of People's Hearts to free Kairi's in Kingdom Hearts. As something interesting, even noted by Ansem the Wise in KH3D, Sora was able to return to his human form without destroying Roxas first.
The Heartless emblem appears to be based on the X-blade's keychain while the Nobodies' is based on the Mark of Mastery (the emblem Eraqus, Terra, Aqua and Ventus wear).
The Unversed (アンヴァース Anvāsu?) are creatures that appear in Kingdom Hearts Birth by Sleep, prior to the Heartless and Nobodies within the continuity. Being extensions of Vanitas that feed off the negative emotions of people, the Unversed are used by Master Xehanort as the foundation of his master plan to obtain the ultimate powers of darkness. All Unversed have eyes that express either joy, sorrow, or rage. It would seem they can alter their size at will as miniature Unversed fought a shrunken Ventus in "Castle of Dreams"; the forms they take also fit in with the worlds they appear in. It appears boss-level Unversed can be created when they feed off the negative emotions of someone, without the help of Vanitas, as Symphony Master and Cursed Carriage appeared when Lady Tremaine grew jealous or angry with Cinderella. The Magic Mirror was also turned into an Unversed by the Queen using one of her potions (or darkness in the Japanese version). Upon defeat, all Unversed (not counting the Magic Mirror) vanish in blue flames. The Unversed cease to be after Vanitas integrates back into Ventus and is subsequently destroyed within Ventus's subconscious. The Unversed are described by Nomura as being "those who were not well-versed in their own existences." However, Vanitas' cameo in Dream Drop Distance may foreshadow that the Unversed returning in the final chapter of the "Dark Seeker Saga".
Kingdom Hearts coded sees the inclusion of software bugs, simply referred to in-game as "bugs", as the game's main antagonistic force. These bugs appear after the contents of Jiminy Cricket's journal are digitized, corrupting the data therein, as an unintentional side-effect of Naminé leaving an extra message inside the journal for Sora and his friends to investigate. They primarily take the form of "Bug Blox" (バグブロックス Bagu Burokkusu?), which are cubes that the game's main protagonist, a virtual replica of Sora called Data-Sora, can destroy or use as platforms. There are several different varieties of Bug Blox, the most common, breakable variety being black-and-red in color. Other bugs take the appearance of boss-level Heartless that Sora had defeated in Kingdom Hearts. Villains, such as Pete, Data Hades, Data Jafar, as well as boss-level Heartless make use of the bugs to assist them in fighting Data-Sora. The original bug responsible for corrupting the journal's data takes the form of Sora's Heartless, and displays sentience as it tries to delete all of the data inside the journal. While its most basic form is the weak and common "Shadow" variety of Heartless, it grows increasingly powerful to the point where it takes other forms, such as an entirely black lookalike of Sora with yellow eyes, or a gargantuan variety of Heartless called "Darkside". The bugs cease to be after Data-Sora destroys the original bug and resets the entire datascape.
Dream Eaters (ドリームイーター Dorīmu Ītā?) are the main enemies of Kingdom Hearts 3D: Dream Drop Distance. Like the Heartless, they are created from darkness and are compelled to find the keyholes of worlds. In contrast to the Heartless, however, Dream Eaters originate from the darkness created in worlds that are in a state of "deep sleep" and are isolated from other worlds. Though Dream Eaters usually manifest as "Nightmares", creatures that devour good dreams and create bad ones, there are also "Spirits" that do the opposite by destroying Nightmares and leaving good dreams and function as Sora and Riku's partners. When a Nightmare appears, it starts as a crystal that swallows smoke in the shape of hearts; their defeat cause the opposite action to occur. The boss Nightmares obey the villains of each world. The Dream Eaters take the forms of animals or flowers, having roughly around the intelligence of a cat, dog or any other domestic animal. Nightmares can also possess other objects, such as Ventus's Keyblade Armor, when it was protecting Sora, and use any abilities or weapons the possessed have. One can become a Dream Eater by diving into the dreams of others. Normally, they can only exist in worlds trapped in the Realm of Dreams, but they can be given access to the Realm of Light by a Keyblade wielder, such as Sora, and leave their home realm.
Keyblades (キーブレード Kīburēdo?) are key-shaped weapons created to combat darkness and are currently the only thing that can free hearts from a Heartless form, and destroy Nobodies, thus allowing the restoration of complete beings. Keyblades also have the ability to lock and unlock all manner of doors and keyholes. Originally, these Keyblades were crafted in the image of the original "X-blade" by those who wanted the Light within Kingdom Hearts for themselves, and those who sought the opposite. Keyblade Masters (or those on the level of Master) can bequeath the power to wield a Keyblade to one they deem worthy by letting them touch the handle of the blade (in Riku and Kairi's case) or connecting their heart to another (in Sora's case); though one can lose their original Keyblade (as in Riku's case), a new one can be born from a different weapon (seen in Riku case; Lea's Chakrams did not evolve into his Keyblade, but he rather can still summon both since they are different weapons).
A Keyblade changes in both appearance and strength with different keychains, which augment its wielder's fighting capabilities; some can be obtained as a result of in-game events, while others can be obtained by completing mini-games. A driving element to the first game is the ability to seal the "heart" of a world by locking the keyhole to the door leading to it, preventing it from being destroyed by Heartless. In Kingdom Hearts II, the player uses the Keyblade to unlock pathways between worlds that were closed after the events of the first game. While Sora is the only one who uses the Keyblade in the first game, later games reveal more characters who wield Keyblades. In Birth by Sleep, Keyblades can be transformed into hovercrafts called Keyblade Gliders, which can be used to travel from world to world, making Keyblade wielders the only people with the means of transportation between worlds before Gummi Ships are used. The "Gates" Sora would open later are known as the Lanes Between, which can be accessed by any Keyblade wielder.
The χ-blade (χブレード Kīburēdo?, pronounced the same as "Keyblade") is an ancient weapon of unknown origin introduced in Birth by Sleep that is capable of directly unlocking Kingdom Hearts. It is a double-handed weapon that takes the shape of two "Kingdom Key" Keyblades that intersect in an "X" shape, with additional features that give it the shape of an actual sword. The weapon has the power to open the heart of all worlds, and unlike ordinary Keyblades, which exist to join Kingdom Hearts, it exists alongside Kingdom Hearts as its guardian. It led to "Keyblades" being crafted in its image by those seeking Kingdom Hearts' power, those who sought to extinguish the light, and those who sought to protect it. The end result was the Keyblade War, which ended in a world known as the Keyblade Graveyard; the aftermath led the χ-blade itself to shatter into seven lights and thirteen darknesses. These seven lights later became the hearts of the Princesses of Heart; what became of the thirteen darknesses is left to specualtion, with the possibility of two being the hearts of Maleficent and Master Xehanort.
In Birth by Sleep, Master Xehanort knew of how to properly create the X-blade, but was too eager to have the weapon in his possession; he attempted to recreate the χ-blade by having two hearts of equal strength—one of pure light and one of pure darkness—clash with each other due to impatience. He found such a means through his former apprentice Ventus and the youth's personified darkness Vanitas, whom Xehanort created and enlisted to ensure his plans succeed. Though Ventus and Vanitas fuse back into one being with the χ-blade in hand, the reunion was not complete as the unstable χ-blade eventually exploded due to Vanitas being destroyed within by Ventus.
After his revival in the events of "Dream Drop Distance," Xehanort admits that his plan involving Ventus and Vanitas was hasty yet has arranged the formation of his Thirteen Seekers of Darkness, the new Organization XIII composing of his various incarnations and vessels, to fight the Keyblade users who would form Seven Guardians of Light, or target the Princesses of Heart, to recreate the χ-blade. However, due to Lea stopping him from turning Sora into his final vessel, Xehanort's organization is one member short, though his group's conflict with the Seven Lights will happen soon.
The titular "Kingdom Hearts" is the "heart of all worlds" and the source of hearts, being in the shape of heart-shaped moon. It is an object of immense power and a central plot element that drives the conflict within the series as its light drove many to fight over it ages ago in what became the Keyblade War. In the end, Kingdom Hearts was consumed in the darkness caused from the conflict and the worlds became separate from each other. The return of Kingdom Hearts was sought by Master Xehanort. While Kingdom Hearts did appear over the Keyblade Graveyard, the flawed reunion of Ventus and Vantias made the χ-blade unstable and Kingdom Hearts remained until its counterpart exploded. Regardless of the set back, Xehanort had a back-up plan: After splitting himself into a Heartless and a Nobody, Ansem (Xehanort's Heartless) seeks out the Door to Darkness to find the actual Kingdom Hearts while Xemnas (Xehanort's Nobody) sought to create his own version of Kingdom Hearts.
Though only touched upon as a sphere of light beyond a white door which "Ansem" (Xehanort's Heartless) was intending to open somewhere within the End of the World, Kingdom Hearts' role is expanded when Xemnas uses Organization XIII to create his own Kingdom Hearts on the notion that it would complete their existences using Roxas and Xion's ability to wield the Keyblade to defeat enough Heartless to form Kingdom Hearts over the World That Never Was; however, this was actually a ruse, since Xemnas actually planned to place Master Xehanort's heart amongst the rest of the group. After Xion's demise and Roxas' departure, the Organization uses Sora to fulfill their plans instead until Ansem the Wise's sacrifice reduces the amount of hearts it is composed of. Xemnas absorbs the rest of it for greater power, but is ultimately defeated and all the hearts are freed, allowed to return to their original owners.
In the Kingdom Hearts universe, travel between worlds is not normally possible. Worlds are protected from extraterrestrial interference by an invisible shell. When the heart of a world is opened, the shell breaks apart, appearing as a meteor shower. Fragments from the wall are called "Gummi blocks" and can be used to make spaceships called "Gummi Ships", which serve as the main mode of travel between the various worlds. Gummi Ships can be shaped into any structure, and the origin of the Gummi Ship material allows for travel to other worlds. Gummi blocks can serve different functions, from navigation to offense and defense. Other methods to travel between worlds are the "corridors of darkness" and the "lanes between"—interdimensional pathways through which frequent travel eventually erodes the user's heart with darkness. These pathways are normally used by Heartless and Nobodies, but have been used by other characters in the series, including Riku and Mickey Mouse.
Those who travel between worlds are advised to limit their interactions with the inhabitants of foreign worlds in order to maintain the world order. For this reason, the main characters change their appearance in certain worlds to avoid standing out. In the worlds based on The Little Mermaid and The Nightmare Before Christmas, Sora, Donald, and Goofy transform into undersea creatures and Halloween monsters, respectively. For The Lion King, they transformed into animals (or, in Donald and Goofy's case, less humanoid forms) because Nomura felt that it would appear odd to have Sora and the others interact in their standard forms, since no humans appear in that film. Also for the Space Paranoid world in Kingdom Hearts II Sora, Donald & Goofy are transferred into data and have grey armor with blue designs, much like the recurring character for that world, Tron.
The majority of worlds that appear in the games are based on Disney films. Most of these worlds, such as Wonderland, the Land of Dragons, and Deep Jungle, follow abridged versions of the stories found in their respective films. Agrabah notably covers the first two Aladdin films in Kingdom Hearts and Kingdom Hearts II, while Atlantica and Halloween Town only mirrors its films in the second game, having an unrelated plot in the first game. On the other hand, worlds like Monstro and Neverland focus heavily on the main Kingdom Hearts plot, the latter being reduced to Captain Hook's ship, where Riku reveals to Sora that Kairi has lost her heart. Beauty and the Beast is an interesting case—the Beast appears in Kingdom Hearts to aid Sora when he temporarily loses the Keyblade. After Beast's Castle is restored at the end of that game, the Beast becomes a pawn in the plot of Organization XIII during Kingdom Hearts II.
During the development of Kingdom Hearts II, Nomura had more creative freedom due to advances in technology. Port Royal, Space Paranoids, and Pride Lands, in particular, benefited from these advances. In Port Royal and Space Paranoids, the character models were generated from live-action pictures using a new program. Nomura had wanted to include a world based on The Lion King in the first game, but could not since its engine could not process quadrupedal character models properly, a feature which was resolved for Kingdom Hearts II. A sub-world of Disney Castle is Timeless River, meant to be the "past" of Disney Castle, shortly before it was built. The world is portrayed in black and white; Nomura had intended it to be this way from the beginning of development. The world has many throwback effects including intentionally poor sound quality to imitate old cartoons. In this grayscale world, Sora's character model is simplified to the style of early cartoons, while Goofy and Donald Duck revert to their original designs from when they first appeared in Disney cartoons. In Kingdom Hearts 3D: Dream Drop Distance, Country of the Musketeers served as a basis for the movie, Mickey, Donald, Goofy: The Three Musketeers. Notably, it is the first world in the Kingdom Hearts series originating from a direct-to-video feature instead of a film from the Disney animated features canon.
In addition to the Gummi Ship minigame, minigames feature prominently in certain worlds. The 100 Acre Wood in all three games consists entirely in minigames based on classic Winnie the Pooh shorts, with Sora taking on the role of Christopher Robin. Olympus Coliseum features optional fighting tournaments; due to Hades' popularity, the Underworld was added in Kingdom Hearts II, where Hades has opened his own tournament. While Atlantica is a normal world in Kingdom Hearts, albeit with a special "underwater" control scheme, it becomes an interactive rhythm game in Kingdom Hearts II which is completely unrelated to the overall story and serves as mere filler. Finally, Space Paranoids features a Light Cycle mini-game that strongly deviates from the original film. Nomura included this minigame because he knew people associated the Light Cycles with Tron. Kingdom Hearts Birth by Sleep introduced several new Disney-based worlds to the series, such as Castle of Dreams, Enchanted Dominion, Dwarf Woodlands and Deep Space. Kingdom Hearts 3D: Dream Drop Distance introduced more new Disney worlds, such as La Cité des Cloches, Prankster's Paradise, Country of the Musketeers, Symphony of Sorcery, and The Grid.
The worlds created specifically for the series predominantly feature original and Final Fantasy characters and figure more centrally to the overarching plot of the Kingdom Hearts series. The first world of each game serves as a tutorial to introduce new gameplay elements and frame the story. Destiny Islands, the home world of the main characters, Sora, Riku, and Kairi, serves this function at the beginning of the first game and Kingdom Hearts Re:Coded. The next available world serves as a hub world, where the player returns multiple times throughout the game to unfold the main story. Traverse Town, a world cobbled together from the remains of worlds destroyed by the Heartless, fills this role in Kingdom Hearts, but becomes the tutorial world in Kingdom Hearts: Chain of Memories. The penultimate world of each game wraps up many plot threads in preparation for the final world. Hollow Bastion is this world for Kingdom Hearts, but, in Kingdom Hearts II, it is the hub world. Twilight Town is both the tutorial world and the penultimate world in Kingdom Hearts II, containing a secret pathway to the final world of that game. The final world culminates in a battle with the main antagonist of the game. End of the World, made out of the worlds that lost their hearts to the Heartless, and the World That Never Was are the final worlds of Kingdom Hearts and Kingdom Hearts II, respectively. Kingdom Hearts: Birth by Sleep differs slightly, however. In its case, the Land of Departure serves as the tutorial world, hub world and where the plot threads wrap up. The final world in the game is the Keyblade Graveyard, where each of the main characters' final battles take place (except Aqua).
Hollow Bastion plays a central role in the backstory of the series, as the home world of a majority of the Final Fantasy characters who appear in Kingdom Hearts, as well as the original home of Ansem the Wise, the ruler of that world, then called the Radiant Garden, and Kairi, who was sent to the Destiny Islands as part of an experiment conducted by Ansem's apprentice, Xehanort. Ansem studied the darkness in people's hearts with six apprentices, including Xehanort. His apprentices continued this dangerous research without his permission, causing the world to become overrun by darkness. Deserted, the castle was later adopted by Maleficent as a headquarters. Castle Oblivion, another villainous hideout and the main setting of Kingdom Hearts: Chain of Memories, consists of multiple floors which transform into memory-based reconstructions of other worlds, via special cards. Finally, Organization XIII is based in the World That Never Was, a world in the in-between realm that houses Kingdom Hearts. This conception of Kingdom Hearts was designed to appear as the heart-shaped moon from the cover of the first Kingdom Hearts game. When the scenario writer, Kazushige Nojima, created the scenario, he described it as a moon floating in the World That Never Was. Upon reading that, Nomura thought of using the visuals from the first game to create a connection.
The series' setting has garnered a mixed to positive reception from critics. Following Kingdom Hearts's initial announcement, publications expressed skepticism towards the first game's viability. Andrew Reiner of Game Informer stated that despite the extreme differences between Final Fantasy and Disney properties, they blend well together along with the new content created for the series. A second Game Informer reviewer, Matt Miller, described the concept as a "hard sell", describing the combination of the two properties as "ridiculous". Though in contrast, he stated the franchise's formula is successful. The graphics of the games have received generous praise, with particular focus on their similarity to the source material. IGN stated that the "worlds look very much like their filmed counterparts". Japanese gaming site, Gpara.com also praised the look of the worlds. GameSpot referred to the worlds as "wonderfully rich familiar environments", and GamePro described the worlds as "spot-on with the original movies."
Following the release of the first game, the Disney settings were well received by critics. Allgame's Scott Marriott stated the Disney settings are the most attractive feature of the game and considered some of the world choices a surprise. He praised the level designs, commenting that a good amount of familiar elements from the Disney films were integrated into them. Marriott further stated that though the stages were small, interacting with beloved characters and exploring familiar settings were enjoyable aspects. Maura Sutton of Computer and Video Games attributed the Disney elements as a major factor in creating the game's "astounding worlds". She summarized her review by calling Kingdom Hearts a "delightful mixture of two enchanted worlds". Video game critics of Kingdom Hearts: Chain of Memories expressed disappointment at the limited number of new worlds to explore in the game. 1UP.com's Bryan Intihar lauded Kingdom Hearts II's environment, calling it appealing and stating it was an improvement over the first title's. He described the level designs as "impeccable", citing the presentation of Timeless River stage's atmosphere. Intihar further commented that the expansions and changes to previous worlds made them "feel fresh". In contrast, Reiner described the Disney elements in Kingdom Hearts II as "tacked on".
- Birlew, Dan (2003). Kingdom Hearts Official Strategy Guide. BradyGames. ISBN 0-7440-0198-6.
- Square Co. (2002). Kingdom Hearts Instruction Booklet. Square Co., Limited.
- X-Play staff (2003-10-27). "Tetsuya Nomura on the 'Kingdom Hearts' Sequels". X-Play. Archived from the original on 2006-08-14. Retrieved 2009-08-07.
- Gantayat, Anoop (2004-09-23). "TGS 2004: Tetsuya Nomura Q&A". IGN. Retrieved 2009-08-07.
- "Playstation.com Europe — E3 Interview". Kingdom Hearts Ultimania. Retrieved 2007-07-23.
- "Nomura Interview Dengeki 1". Kingdom Hearts Ultimania. Retrieved 2007-07-18.[dead link]
- "Kingdom Hearts II Tetsuya Nomura interview". Video Game Blogger. Retrieved 2007-07-21.
- "KHU Interview w/Tetsuya Nomura". Kingdom Hearts Insider. Retrieved 2007-08-10.
- "Dengeki — Kingdom Hearts 2 Progress Report". Kingdom Hearts Ultimania. Archived from the original on 2007-06-08. Retrieved 2007-07-27.
- "Nomura Dengeki Interview #3". Kingdom Hearts Ultimania. Archived from the original on 2007-06-11. Retrieved 2007-07-18.
- Secret Ansem Report #4: Three elements combine to create a life: a heart, a soul, and a body. [...] Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Ansem's Report 10: Just as people have hearts, so do worlds. The same can be said of stars in the night sky. And deep within each world lies a door to its heart. Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts.
- Square. Kingdom Hearts 2. PlayStation 2. Square Electronic Arts.
- Secret Ansem Report #7: When a Heartless is born, the body and soul left behind are reborn into this world as a different being. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Secret Ansem Report #3: I, too, have had everything taken away from me, banished to a hollow realm of nothingness. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Secret Ansem Report #5: Not only did they generate "pureblood" Heartless from living hearts, but they then used those Heartless to synthesize artificial versions of the creatures as well. These synthetic Heartless bore insignias and were called "Emblem Heartless." Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Saïx: The Heartless ally with whoever is the strongest. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Yen Sid: The Heartless and the Nobodies will be using their own paths: Corridors of darkness, to travel from world to world. They may be attempting to link these dark pathways to the gates between the worlds. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Yen Sid: An empty vessel whose heart has been stolen away... A spirit that goes on even as its body fades from existence---for you see, Nobodies do not truly exist at all. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Secret Ansem Report #7: A great number of Nobodies have lost human form, as have the Heartless. Yet the Nobody born of someone with a strong heart retains its shape, with but the faintest visible changes. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Studio BentStuff, ed. (2005). Kingdom Hearts II Ultimania (in Japanese). Square Enix. ISBN 4-7575-1621-5.
- "2nd Famitsu Nomura Interview". Kingdom Hearts Ultimania. Archived from the original on 2007-08-04. Retrieved 2007-09-20.
- Yen Sid: Xehanort's heart, once seized by his Heartless half, is now free. And his body, which had become his Nobody, has been vanquished. Both halves will now be returned to the whole. Square Enix (2011-01-11). Kingdom Hearts Re:coded. Nintendo DS. Square Enix.
- Xemnas: A heart is never lost for good. There may have been variances in our dispositions, but a number of us unquestionably showed signs of a burgeoning replacement. Once born, the heart can also be nutured. Our experiments creating the heartless were attempts to control the mind, and convince it to renounce its sense of self. But understand, one can banish the heart from the body, but the body will try to replace it the first chance it gets, for as many times as it takes. And so I knew, even after we were divided into Heartless and Nobodies, it was just a temporary separation.Square Enix (2012-07-31). Kingdom Hearts 3D: Dream Drop Distance. Nintendo 3DS. Square Enix U.S.A., Buena Vista Games.
- Yui (2008-08-02). "KH Birth by Sleep：DKΣ3713初の試遊台出展レポート、新たな敵は「アンバース」" (in Japanese). Retrieved 2008-08-03.
- "Interview with Tetsuya Nomura and Hajime Tabata" (translation). Famitsu: p 33. October 2007. Archived from the original on June 13, 2008. Retrieved 2008-08-20.
- Information regarding KH3D's new enemy at TGS
- Saïx: Pitiful Heartless, mindlessly collecting hearts. And yet they know not the true power of what they hold. The rage of the Keyblade releases those hearts. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Marluxia:: The rest of us can defeat Heartless, but we have no way of collecting the hearts they release. Eventually, the hearts will turn right back into Heartless. Square Enix (2009-09-29). Kingdom Hearts: 358/2 Days. Nintendo DS. Square Enix.
- Hades: Let me see if I got this right... That brat's Keyblade works on any lock? / Pete: That's right. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Yen Sid: Because of your previous endeavors, the worlds have returned to their original states. That means the pathways between them have disappeared. / Donald: How do we get around? / Yen Sid: Do not fear. If what the King suspected proves true, the worlds have prepared new pathways along which you may travel. These pathways may be utilized by unlocking special gates. How these gates are opened, I'm afraid I do not know... However, the Keyblade will serve as your guide. When a beam of light radiates from the Keyblade, return to the Gummi Ship. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Famitsu Staff (2009-12-10). Weekly Famitsu (in Japanese) (Enterbrain): 48–55.
- Kairi's grandmother: Long ago, people lived in peace, bathed in the warmth of light. Everyone loved the light. Then people began to fight over it. They wanted to keep it for themselves. And darkness was born in their hearts. The darkness spread, swallowing the light and many people's hearts. It covered everything, and the world disappeared. But small fragments of light survived, in the hearts of children. With these fragments of light, children rebuilt the lost world. It's the world we live in now. But the true light sleeps, deep within the darkness. That's why the worlds are still scattered, divided from each other. Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts.
- "Another Report" interview translated". Kingdom Hearts Insider. 2007-04-17. Archived from the original on 2007-06-20. Retrieved 2007-08-22.
- Yuffie: Before all this, you didn’t know about the other worlds, right? / Aerith: Because every world was isolated. Impassable walls divided them. Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts.
- Ansem's Report 5: Suddenly, a strange door appeared. I'd never known of its existence. It had a large keyhole, but didn't seem to be locked. So I opened the door. What I saw on the other side mystified me. What was that powerful mass of energy. That night I observed a great meteor shower in the sky.Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts.
- Ansem's Report 9: Simply astonishing! Today I had a guest from another world. He is a king, and his vessel is built of the material that composed the meteors. He called the pieces "Gummi blocks." It seemed that my opening the door has opened a path to interworld travel. Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts.
- Hollinger, Elizabeth (2006). Kingdom Hearts II Official Strategy Guide. BradyGames. ISBN 0-7440-0526-4.
- Goofy: Oh, right... I gotcha. While we’re in the other worlds, we can’t let on where we’re from. We’ve gotta protect the world border. / Donald: Order. Square (2002-11-15). Kingdom Hearts. PlayStation 2. Square Electronic Arts.
- Triton: As the Keybearer, you must already know that one must not meddle in the affairs of other worlds. Square (2002-11-15). Kingdom Hearts. PlayStation 2. Square Electronic Arts.
- Donald: Okay, guys. Prepare for landing. / Sora: Land where? In the sea? We’ll drown! / Donald: Not with my magic, we won’t. Just leave it to me. Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts.
- Goofy: This sure is a spooky place. I’ll bet the people here are scary-lookin’ too. / Donald: Don’t worry. We look spooky, too. If they scare us, we’ll scare them right back! Square Co., Limited. Kingdom Hearts. PlayStation 2. Square Co., Limited.
- Goofy: Let's see...if that door's connected to the past... / Donald: No, no, no! It comes here. / Sora: Huh? / Goofy: Then that means we're in the past! Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Kingdom Hearts Series Ultimania α ~Introduction of Kingdom Hearts II~ (in Japanese). Square Enix. 2005. ISBN 4-7575-1597-9.
- Bryan Boulette (2005-11-27). "Nomura Divulges Kingdom Hearts II Details". RPGamer. Retrieved 2007-07-23.
- Kingdom Hearts II Piggyback Guide. Piggyback Interactive Limited. 2006. ISBN 978-1-903511-89-3.
- Goofy: Gawrsh, is that all that's left of the worlds taken by the Heartless? Square Co., Limited. Kingdom Hearts. PlayStation 2. Square Co., Limited.
- Tron: You can see the town back when it was first built. / Leon: That's right... I remember now. / Cid: Just like the old days... / Merlin: Hmm... I'd be fascinated to ascertain as to when the town got such a dreadful name as Hollow Bastion! / Aerith: You know, this town had another name once. / Sora: Hm? / Aerith: Radiant Garden. Square Enix (2006-03-28). Kingdom Hearts II. PlayStation 2. Square Enix U.S.A., Buena Vista Games.
- Ansem Report 10: "However, as for one possibility, an experiment. She can lead me to the place where the person who possesses the "Key" is... I will try sending her to the sea of the strange sky. (アンセムレポート10: しかし、これは一つの可能性であり、実験である。彼女が鍵を持つ者のいる場所へ私を導いてくれるのか… 異空の海に送り出してみよう。?) Square (2002-12-16). Kingdom Hearts Final Mix (in Japanese). PlayStation 2. Square, Disney Interactive.
- Fennec Fox (2002-09-30). "Kingdom Hearts Review". GamePro. Bob Huseby. Archived from the original on 2008-12-27. Retrieved 2009-08-18.
- Gerstmann, Jeff (2001-10-12). "TGS 2001 FallKingdom Hearts hands-on". GameSpot. Retrieved 2009-08-18.
- Harris, Craig (2004-12-13). "Kingdom Hearts: Chain of Memories". IGN. Retrieved 2009-09-01.
- Reiner, Andrew; Matt Miller. "Kingdom Hearts 2 Review". Game Informer. GameStop Corporation. Archived from the original on 2008-05-03. Retrieved 2009-08-18.
- Jeff Haynes (2006-03-28). "Kingdom Hearts II". IGN. Retrieved 2006-12-15.
- "Review：大好きなディズニーキャラと、いつも一緒にいられる喜び。『KHII』レビュー" (in Japanese). Gpara.com. 2006-01-24. Retrieved 2007-07-16.
- Carrie Gouskos (2006-03-28). "Kingdom Hearts 2". GameSpot. Retrieved 2007-07-24.
- Fennec Fox (2002-09-30). "Review: Kingdom Hearts for PS2 on GamePro.com". GamePro. Archived from the original on 2008-12-27. Retrieved 2007-07-05.
- Marriott, Scott Alan. "Kingdom Hearts — Review". Allgame. Retrieved 2009-09-03.
- Sutton, Maura (2002-11-30). "PS2 Review: Kingdom Hearts". Computer and Video Games. Retrieved 2009-09-03.
- Reiner, Andrew. "Kingdom Hearts: Chain of Memories". Game Informer. Archived from the original on 2008-05-03. Retrieved 2009-09-01.
- Intihar, Bryan (2006-04-14). "Kingdom Hearts 2 Review". 1UP.com. Retrieved 2009-09-03.