Kiss×sis(キス×シス,Kisu×shisu?) is a Japanese seinenmanga written and illustrated by Bow Ditama. It began serialization in Bessatsu Young Magazine (now Young Magazine) on December 11, 2005 and has since been published into ten volumes by Kodansha. The series was later adapted into two animated series by Feel; a twelve-episode television show aired from April 5 to June 21, 2010 by AT-X, and an ongoing original video animation series since December 22, 2008.
Keita Suminoe is a third-year Japanese middle school student living with his father, stepmother, and older twin stepsisters, Ako and Riko. Since the remarriage of their parents at childhood, the siblings have always been affectionately close and supportive of one another. Picking up at least a decade later, the trio, now teenagers, see their opposites in a noticeably less platonic fashion; Ako and Riko frequently flirt and lust after Keita while, much to his stress, he fights the urge to give into them.
Keita Suminoe is the main protagonist of the series. Blended into a step-family when, at childhood, his father remarries (his birth mother passed away when he was young), he comes into the acquisition of a stepmother and older stepsisters, Ako and Riko; an arrangement he welcomes. A 15-year-old, third-year middle school student, and under the now persistent debauchery of his siblings, Keita finds it increasingly difficult to retain his modest, dignified morals; especially when his parents encourage him to indulge. A former track and field member, Keita is athletic more than he is academic; however he strives to and eventually is accepted to his stepsisters' high school. There, he is a first-year high school student in the same class as Miharu, with Yuzuki Kiryu as their homeroom teacher.
Bright and cheery, Ako Suminoe is a 16-year-old, first-year high school student who is one of two stepsisters to Keita, twin sister to Riko. The more intellectual of the pair, Ako is educated, maternal, responsible, President of the student council, skilled at cooking, homemaking, and endeavors to maintain a prim and proper demeanor. In spite of this imposing façade however, she is outwardly emotional, childish, whiny, reluctant, easily embarrassed and perverse; her most well-known open secret. Having grown up with Keita since toddlerhood, Ako is altruistic and, of course, in love with him. As such she isn't afraid of abusing her authority on the student council to either make a pass at Keita, or cover up an embarrassing occurrence such as when she asked Keita to pick up her, Riko's, Miharu's, and Kiryu's alternate clothes when Sensei and the twins (Miharu was in a stall that was hit with a wild shot) got into a severe water fight in the girls' bathroom over the twins' romantic interest in Keita.
Riko Suminoe is the second stepsister to Keita; a fellow 16-year-old, first-year high school student. Though less accomplished than her counterpart, Riko is interpersonal, cunning, insightful, crafty, an active member of the disciplinary club, and boldly open about her personal life and sexuality; although she surprisingly cannot bring herself to kiss Keita in front of others. However, unlike Ako she is highly skilled in physical activities and sometimes helps out with various sports clubs who need another person temporarily for training. She is known however, to be soft-spoken, clumsy, temperamental and weaker to alcohol than her sister. Riko is most recognized for wearing an adhesive bandage on her left cheek, the purpose of which covers a scar she received from when Keita threw a toy at her during their childhood. Although this is more to keep Keita thinking about her than to cover the scar as there is a chance that the scar might be negligible if not unnoticeable to view since she never lets anybody see what's under the bandage, such as instantly dashing to a store, buying and applying a new bandage, and racing back to where she started from when Kiryuu-sensei removed an old bandage during a trip to the beach. In a complimenting fashion, Riko is also ardently fond of her stepbrother and forever fighting with Ako over his affections.
Miharu Mikuni is a third-year middle school student who enters into the same high school class as Keita. A fairly quiet and unknown character, she is brought into attention when she delivers Keita his entrance exam results; having passed, he joyfully befriends her. Unlike the other girls, Miharu is comparatively tacit, meek, intimidated and predisposed to anxiety; as such, she suffers from enuresis (this becomes a running gag in the series). Her relationship with Keita is mostly platonic; what feelings she does have for him are generally overshadowed by the images she has of him and his stepsisters. She sometimes fantasizes about Keita making non-consensual advances against her, but doesn't have any romantic interest in him for most of the chapters after meeting him. Although she seems to be (glacially) slowly developing an interest in him due to him helping her out and keeping his mouth shut about various (and sometimes extremely embarrassing) events (usually but unintentionally caused by either the twins or Kiryu) such as when he ducked down during a race (and hurting his leg a little) so she'd be the one to break the tape at the finish line and experience what it felt like to win in a sports event. Of the entire cast, Miharu is the only bespectacled character.
Peppy and outgoing, Mikazuki Kiryu is a second-year middle school student and younger sister of Yuzuki Kiryu. She enters third-year middle school when Keita starts his first year in high school. In spite of her age, she is far more mature of the two, and tends to keep the most level head when her sister is losing hers. An underclassman to the rest of the cast, Mikazuki looks up to everyone, especially Keita, who she fashionably has a crush on. However, she seems to be just as interested in amusing herself by watching the antics and reactions of others than actually winning him over. Considers her sister Yuzuki and Keita to be two of a kind, well suited for each other, and enjoys watching them try to act like a normal teacher and student. Although she seems to be developing some feelings for Keita herself after the group trip to the beach. Mikazuki lives with her parents and is the shortest character of the entire cast. She shares a certain genetic condition with her sister that is revealed when the girls are having a bath during the beach trip.
Yuzuki Kiryu is a 23-year-old homeroom and Japanese History teacher at fictional Gakushū Senior High, a recent hire, and is also the older sister of Mikazuki. While she constantly berates herself whenever she makes mistakes, she is a caring teacher who can lay down the law when she wants to but tends to get herself and others in trouble when she acts impulsively over perceived things without finding out the full story. One example is that she does not realize that Ako and Riko are Keita's stepsisters, not his biological sisters, until they tell her. Single, unmarried, independent, and noticeably eccentric, she is initially disgusted with Keita and his relationship with Ako and Riko, to the point of unduly crusading against it. Ultimately, like the girls to come, and despite her age difference, she develops conflicting feelings for Keita herself. An obsessive fan of anime, manga and cosplay, Yuzuki's apartment spans a large collection of merchandise, books, games and posters; a particularly favored theme of hers being samurai. She is so obsessed that her parents forced her to either get a place of her own (which she did) or give up her hobbies permanently. She often has to eat cheap ramen as she spends most of her money on so much paraphernalia to clutter her room and apartment that she can't invite anyone inside without them discovering her hobby. Much to her humiliation, Yuzuki is a virgin. In the manga, Yuzuki and Keita eventually become closer and start dating in secret, a fact only known by Ako and Riko, who despite being angry at her for getting involved with her own student, respect his decision, claiming to her that in the end they will have him return to their side.
Kiss×sis began as a series of one-shots in January 2004 by Bow Ditama, an illustrator known for his work on Mahoromatic, published by Kodansha in their now-defunct bimonthly Bessatsu Young Magazine, a manga magazine aimed at a mostly adult male audience.Kiss×sis transferred to Weekly Young Magazine in September 2008, and again transferred to Monthly Young Magazine on December 9, 2009. The first tankōbon volume was released on September 6, 2007 by Kodansha under their KC Deluxe imprint, and 10 volumes have been released as of July 6, 2012; volume 11 will be released in 2013. The manga is also licensed in Taiwan by Sharp Point Press.
It was announced in June 2008 that an animated adaption of Kiss×sis would be produced by Feel. On December 22 of that year, the first OVA was released, bundled with the third volume of the manga, directed by Munenori Nawa. Subsequent releases were packaged with subsequent volumes of the manga: the second episode was bundled with volume four on May 22, 2009, the third with volume five on November 20, four with volume six on June 4, 2010, five with volume seven on November 22, 2010, six with volume eight on June 22, 2011, seven with volume nine on November 30, 2011, eight with volume ten on July 6, 2012 and nine with volume eleven on February 6, 2013. The opening and closing themes for the OVA include "Our Honey Boy" (ふたりのハニーボーイ,Futari no Hanibōi?) by Ayana Taketatsu and Yuiko Tatsumi and "Starry Sky Story" (星空物語,Hoshizora Monogatari?) by Nana Takahashi, respectively.
A 12-episode anime TV series adaptation of the manga aired on AT-X between April 5 and June 21, 2010. A censored pre-release of the first episode aired online on March 28, 2010. The opening theme is "Balance Kiss" (バランスKISS?) performed by Ayana Taketatsu and Yuiko Tatsumi, and the ending theme is "Our Steady Boy" by Yui Ogura and Kaori Ishihara. The ending theme for episode 12 is "Futari" (ふたり?) by Yui Ogura and Kaori Ishihara. The first DVD volume was released on June 23, 2010. Unlike the TV airings of the other episodes, certain scenes of episodes nine through twelve were censored. A Blu-ray Disc edition has subsequently been released without the censorship.