The Kissxsismanga, written and illustrated by Bow Ditama, is an ongoing seinen publication that premiered as a one-shot in the January 2004 issue of Bessatsu Young Magazine, a bimonthly periodical circulated by Kodansha. The story, a comedic slice of life, centers on Keita Suminoe, a fifteen-year-old middle-turn-high school student who is the frequent subject of his sixteen-year-old stepsisters' romantic attention.
After being met with largely positive reception from readers, the strip was given regular syndication in December 2005, going on to become a monthly series when Kodansha changed the frequency of its magazine, renamed Young Magazine, on December 9, 2009. News of work to redevelop Kiss×Sis into an animated series first surfaced in the June 2008 issue of Bessatsu Young Magazine; since then, the series has been made into a twelve-episode television show broadcast on AT-X from April 5 to June 21, 2010, and a direct-to-video (OVA) release started December 22, 2008, both produced by Feel.
Kiss×Sis was first collected into a volume on September 6, 2007, by Kodansha under their KC Deluxe imprint, and has been published into a current twelve volumes. Following the release of the second volume, limited edition bundles of the manga and direct-to-video releases of the anime began to be offered. In addition to its domestic release, the manga is also licensed for distribution in Taiwan by Sharp Point Press.
"Let's Start From 0" (ゼロから始ぬよる,"Zero Kara Shi Nuyoru")
"Under One Roof" (ひとつ屋根の下,"Hitotsu Yane no Shita")
"Their Strategy" (ふたいのかけひき,"Futai no Kakehiki")
"Is this What You'd Call a Love Triangle?" (これって三角食べ,"Korette Sankaku Tabe?")
"Qualifications for Being Lovers" (恋人の資格,"Koibito no Shikakua")
"The Guy Who Could Pass" (合格圏内の男,"Goukaku Kennai no Otoko")
"The Good-for-Nothing Guy" (ロクでなしの男,"Rowa Denashi no Otoko")
Keita Suminoe, a fifteen-year-old third-year middle school student, endures the persistent and questionably incestuous affection of his sixteen-year-old stepsisters, Ako and Riko. When end of the year entrance exams begin to approach, Keita makes an effort to regularly attend prep school, leaving the girls for the most part uninvolved; on one such morning, they reminisce about their lives with him four years prior. Back at present time, the girls treat Keita to karaoke for the holidays, a visit that goes awry when an order of drinks are unexpectedly alcoholic.
"Full of Memories" (ハチきれそうな想い,"Hachi Kiresouna Omoi")
"Between Confusion and Frustration" (苦悩と煩悩の間で,"Kunō to Bonnō no Kan de")
"The Reason to Feel Full of Confidence" (十分な気持ちと理由,"Jūbun na Kimochi to Riyū")
"A Good Feeling Tool" (イイ感じのアイテム,"Ii Kanji no Aitemu")
"One, Two, 3P!" (いち、にの、3P!,"Ichi, Nino, 3P!")
Back at home, the group spend New Year's together. In the days following, with exams a month away, Keita finds it increasingly difficult to study with the girls relentless advances; something he finds himself beginning to like and desire. In an effort to bring Keita luck on his upcoming exam, the girls, per an internet search at school, make an omamori of their pubic hair as a gift. Later, partially fueled by their libido, when cleaning Keita's room, the girls find an adult magazine, Ako and Riko put together a makeshift sex doll and masturbate on it.
"Is There a Meaning to This?" (意味あんの？,"Imi Anno?")
"The Day of the Test!" (いよいよ本番!,"Iyoiyo Honban!")
"The Angst of a 15 Year Old Boy" (男15歳の苦悩,"Otoko 15 Toshi no Kunō")
"The Lust of 16 Year Old Girls" (女16歳の煩悩,"Onna 16 Toshi no Bonnō")
"An Unrestrained Night" (自由なナイトタイム!,"Jiyū na Naitotaimu")
Keita comes down with a flu and is bedridden for days as Ako and Riko endeavor to care for him. The morning of the exam arrives and Keita gives it his all; the following day, the group visit an onsen to celebrate. After playing some carnival games, eating lunch, visiting a sex museum, and having dinner, the trio relax in a bath. Ako attempts to take advantage of Keita by inebriating him on beer while Riko manages to seduce him when Ako passes out. In both instances, Keita falls asleep and awakens to remember nothing.
"A Cruel Younger Brother" (残酷な弟,"Zankokuna otōto")
The results of the exams arrive in the mail; Keita's however, go missing when a dog takes his and runs off. That evening, Miharu Mikuni, a fellow student, returns them; Keita has passed. During graduation, the group meet her again and a new acquaintance, Mikazuki Kiryū, an underclassman and friend of Keita's, who all participate in a lottery for his affection. The next day, Keita and the girls go to get him fitted for a new school uniform, meeting a tailor who doubles as his homeroom teacher, Yūzuki Kiryū. Witnessing the trio kiss at school, she makes it a personal goal to dissolve their relationship.
"Dogs Are Going Crazy" (犬がニシ向きゃ,"Inu ga Nishi Mukya")
"Let's Make Tea Turbid" (お茶は濁しましょう,"Ocha wa Nigoshi Mashō")
"After a Midnight Bath" (風呂上りの夜空に,"Furo Nobori no Yozora ni")
"An Unfamiliar Look" (不慣れなカッコ,"Funare na Kakko")
"A Complicated Holiday Season" (フヤけた大型連休,"Fuya Keta Oogatarenkyū!")
"Adorable Sisters" (ニクめない姉妹,"Niku Menai Shimai")
Yūzuki unsuccessfully convinces Miharu to date Keita and for Ako and Riko to stop with their amorous behavior. When a water fight in the women's bathroom leaves Yūzuki without clothes, Keita lends her his P.E. uniform; she brings it home, and in a flash of irony, masturbates to him in it. The next day, rummaging for a cookbook, Riko finds a pornographic magazine amid Ako's bookshelf, inspiring the girls to ask for a computer. The technician who sets it up for the family installs an internet filter however, prompting them to visit Akihabara to purchase an eroge instead. Making their way into the adult section of a video store, the girls bump into Yūzuki and Mikazuki; the two of whom, are revealed to be sisters.
"An Unpredictable Relationship" (見通し不明な関係,"Mitooshi Fumei na Kankei")
"Amazing Contact" (サイコーの密着度,"Saiko no Micchakudo")
"Rewards Taste Like Honey" (ご褒美はミツの味,"Go Houbi ha Mitsu no Aji")
"A Terrible Event" (様々なイベント,"Samazamana Ibento")
"An Interview Without Hindrance" (サシつかえない訪問,"Sashi Tsukaenai Houmon")
"A Magnificent Way to Hide" (見事な隠れかた,"Migoto na Kakure Kata")
Thinking back to all of the embarrassing experiences with Keita, and even having an orgasmic one thereafter, Miharu finds herself mildly attracted to him. After spending an intimate couple of days with Keita, Ako and Riko participate in a school physical, competing with one another for the best scores; despite having crash dieted for a day, Ako loses to the much anticipated weight measurement. On a rainy walk home from school, Mikazuki invites Keita over to her house where the two spend a prurient time together. Yūzuki returns home early, unfortunately, and in spite of a bold effort to hide from what becomes a compromising situation, Keita is found.
"Being Blamed from Start to End..." (責められて...,"Seme Rarete..")
"A Good Girl's Summer Holiday" (よい子の夏休み,"Yoiko no Natsuyasumi")
As a make-up for the previous incident with Mikazuki, Yūzuki arranges a home visit at the Suminoe's; with the rest of the family out for the day however, she spends a scandalous time with Keita instead. Following another passionate couple of days with Keita, Ako and Riko make plans for a summer vacation to either the beach or the mountains. Dissatisfied with the unsupervised arrangement, Yūzuki invites herself to chaperon with Miharu and Mikazuki in tote.
"What Happened in the Middle of the Night" (ヨナカの出来事,"Yonaka no Dekigoto")
"Manipulating Your Younger Brother" (支配される弟,"Shihai Sareru Otōto")
The group decide on visiting the beach for vacation, which everyone spends an enjoyable time at for the day. After checking into a hotel, the gang sit to dinner, go out on a test of courage, and then return to bathe; much to Yūzuki's disappointment, Keita and the girls share a separate room for the night. Sneaking in to check on them, Yūzuki is drawn to Keita when he experiences an erection in his sleep and later when he sleepwalks in on her using the bathroom. Mikazuki, having seen and heard most of this, teases the truth out of her sister; Yūzuki likes Keita. That day, having won a game of rock-paper-scissors to Ako, Riko is given the opportunity to be alone with Keita.
"Since We're All Girls, No Need to Hold Back♪" (女子会なら､ご自由に♪,"Joshi Kai Nara go Jiyū ni♪")
"Beyond Consent!?" (合意のうえで！？,"Goui Nouede!?")
"Horny Ice" (ゴツゴツした氷,"Gotsugotsu Shita Kori")
"Yūzuki Kiryū's Miscalculation" (桐生夕月の誤算,"Kiryū Yūduki no Gosan")
"Go for it!" (same name)
As the second and final day of vacation hits noon, the group return to the beach. Keita, wishing to distance himself from Riko, takes Ako out on a boat in the ocean where the two share a lustful and embarrassing time under the sun. Jumping to midsummer, after spending a hot afternoon French kissing ice cubes with the girls, everyone save for Mikaru attend an Obon festival; toward the end of the night, having made a move to kiss Keita, Yūzuki affirms she is in love with him. As summer vacation comes to an end, Keita, finishing up homework on his birthday, looks optimistically with Ako and Riko about their upcoming second semester at school.
"It........It's a Misunderstanding!!!!!" (ご、誤解あります!!,"Go, gokai Arimasu! !")
"Don't Worry!!" (心配練無用!!,"Shinpai neri Muyō! !")
"That Crushing Feeling" (ユナゴナになりそうな気持ち,"Yunagona ni nari-sōna Kimochi")
"The Forbidden Secret Training" (御法は秘密練習,"Minori wa Himitsu renshū")
"The Best Performance" (極上の演技,"Gokujō no Engi")
"Not as Naive as You'd Think!" (無糖の味は甘くはい！,"Mutō no aji wa Amaku wa i!")
After the vacation trip is over , the first day of the second semester has begun.Since the classmates of Keita envied him about the trip with his sisters during the vacation, Keita looked very depressed and thought about the incident with Yūzuki. Suddenly Mikuni san appeared and greeted him by her own which surprised Keita as well. Keita's friend Toda started to suspect him that Keita made love with Mikuni san in the vacation trip and imagined some perverted scenes which Keita denied at first until he admit that both of them went together on a trip.