Onimai

Onimai: I'm Now Your Sister! (お兄ちゃんはおしまい!) is a Japanese manga series written and illustrated by Nekotofu. The series has been serialized online since 2017; it is also currently serialized in Ichijinsha's Monthly Comic Rex magazine since April 2019. It is licensed in English by Kodansha USA. An anime television series adaptation by Studio Bind aired from January to March 2023; it gained high ratings, although it received a mixed reception from foreign critics.

Plot
The series follows Mahiro Oyama, an otaku and NEET who lives alone with his scientist younger sister Mihari. One day he wakes up to find himself transformed into a young girl, a result of one of Mihari's experiments. Mahiro must now learn to become comfortable in his new body whilst living life as a middle school girl.

Characters

 * Mahiro Oyama (緒山 真尋)
 * The protagonist of the series, Mahiro was previously an otaku man living with his younger sister Mihari until he was turned into a girl as a result of one of her experiments. Mahiro ends up transferring to a middle school. Mahiro is fond of playing video games and mainly stayed at home before being turned into a girl.
 * The protagonist of the series, Mahiro was previously an otaku man living with his younger sister Mihari until he was turned into a girl as a result of one of her experiments. Mahiro ends up transferring to a middle school. Mahiro is fond of playing video games and mainly stayed at home before being turned into a girl.


 * Mihari Oyama (緒山 みはり)
 * Mahiro's younger sister and a scientist. She turned Mahiro into a girl as a result of one of her experiments. Due to her high intelligence, she skipped several grades and is now a university student.
 * Mahiro's younger sister and a scientist. She turned Mahiro into a girl as a result of one of her experiments. Due to her high intelligence, she skipped several grades and is now a university student.


 * Kaede Hozuki (穂月 かえで)
 * Mihari's classmate during middle school and a gyaru. She is Momiji's older sister. She is good at cooking and using cosmetics. She also works part-time at a fast food restaurant.
 * Mihari's classmate during middle school and a gyaru. She is Momiji's older sister. She is good at cooking and using cosmetics. She also works part-time at a fast food restaurant.


 * Momiji Hozuki (穂月 もみじ)
 * Kaede's younger sister and Mahiro's classmate. She has a tomboyish personality and greatly admires Mahiro. She has been friends with Asahi for several years.
 * Kaede's younger sister and Mahiro's classmate. She has a tomboyish personality and greatly admires Mahiro. She has been friends with Asahi for several years.


 * Asahi Ōka (桜花 朝日)
 * Mahiro's classmate. She has an energetic personality but tends to not perform well in tests. She also calls Mahiro by many nicknames.
 * Mahiro's classmate. She has an energetic personality but tends to not perform well in tests. She also calls Mahiro by many nicknames.


 * Miyo Murosaki (室崎 美夜)
 * Mahiro's classmate. She is interested in yuri and tries to hide it poorly. She enjoys imagining her friends in romantic situations. Miyo is notably bustier than her classmates and embarrassed about it.
 * Mahiro's classmate. She is interested in yuri and tries to hide it poorly. She enjoys imagining her friends in romantic situations. Miyo is notably bustier than her classmates and embarrassed about it.


 * Nayuta Tenkawa (天川 那由多)
 * Mahiro's classmate who joins during their second year of middle school. She is a bright, yet shy girl who is the ward of Mihari's faculty advisor Chitose Azuma, who is having her monitor Mahiro without Mihari's knowledge. After revealing to Mahiro that she knows the truth about her, she is quickly accepted into Mahiro's group of friends. She is very knowledgeable due to the many hours she spent in the university library, and speaks in a very polite tone with everyone she encounters.


 * Chitose Azuma (吾妻 ちとせ)
 * Mihari's faculty advisor and senpai at the university Mihari attends, as well as Nayuta's guardian. She made key contributions that allowed for the creation of the drug that turned Mahiro into a girl. Although Mihari believes that she did this out of the goodness of her heart, she is actually using Mihari to fulfill an unknown agenda and enrolled Nayuta into the same class as Mahiro to spy on her without Mihari's knowledge.
 * Mihari's faculty advisor and senpai at the university Mihari attends, as well as Nayuta's guardian. She made key contributions that allowed for the creation of the drug that turned Mahiro into a girl. Although Mihari believes that she did this out of the goodness of her heart, she is actually using Mihari to fulfill an unknown agenda and enrolled Nayuta into the same class as Mahiro to spy on her without Mihari's knowledge.

Production
Prior to creating the series, Onimais author, Nekotofu, was a fan of the "gender bender" genre of anime and manga that included such works as Ranma ½, Kashimashi: Girl Meets Girl'', and '. As such, Nekotofu had harbored a longtime interest in creating his own such series, and was inspired to do so after seeing Your Name. He was also motivated by the positive response to a doujinshi he had created which also featured similar gender-bending elements. Nekotofu began self-publishing Onimai on Pixiv in January 2017, and later on Niconico Seiga, where it became significantly more popular. In April 2019, the manga began serialization in Ichijinsha's Monthly Comic Rex magazine. Nekotofu continues to self-publish the series online and produce doujinshi with permission from Ichijinsha.

Manga
Written and illustrated by Nekotofu, Onimai: I'm Now Your Sister! began serialization online via Pixiv and other platforms in 2017. It also started in Ichijinsha's Monthly Comic Rex magazine on April 27, 2019. As of November 2023, eight tankōbon volumes have been released by Ichijinsha. In North America, Kodansha USA is publishing the series digitally in English.

Anime
An anime television series adaptation was announced on April 22, 2022. It is produced by Studio Bind and chief directed by Shingo Fujii, with Michiko Yokote as head writer, character designs handled by Ryo Imamura, and music composed by Daisuke Achiba and Alisa Okehazama. The series aired from January 5 to March 23, 2023, on AT-X and other networks. The opening theme song is "Identeitei Meltdown" (アイデン貞貞メルトダウン) by Enako feat. P Maru-sama, while the ending theme song is "Himegoto*Crisisters" (ひめごと＊クライシスターズ) by Marika Kōno, Kaori Ishihara, Hisako Kanemoto, and Minami Tsuda. Crunchyroll has licensed the series outside of Asia. Medialink has licensed the series in Asia-Pacific.

Accolades
Onimai: I'm Now Your Sister! ranked fifth in Da Vinci's Next Manga Award 2018 in the web manga category in August 2018, and ranked ninth in Web Manga Overall Election 2019 in October 2019. The manga also ranked third in AnimeJapan's Manga We Want to See Animated Ranking in 2020, and ranked seventh in 2021.

Critical reception
The series received positive reviews and was ranked by viewers in Japan as the top-rated TV anime of the Winter 2023 season on both Niconico and anime ranking website Anikore.jp. One Japanese-language reviewer, writing for 4Gamer.net, echoed positive sentiments regarding its music and art style. Shoki Ota, writing for KAI-YOU, said the series was remarkable for its meticulous depiction of everyday life, and said, "While it might not be for everyone due to its gender swap themes, it feels like a condensed work amid the recent 'anime festival', making it a must-see this season".

In early English-language coverage of the series, the critical response to Onimai's first few episodes were mixed despite high user ratings. Some reviewers criticized the premise and lolicon themes, and perceived incestuous overtones, while praising the animation and music, which was near-universally deemed to be of exceptional quality. Rebecca Silverman was softer in her criticisms, describing the fan service as "relatively toned down" but stated that the narrative premise was "mean" and described as uncomfortable to watch and squandering its potential.

Kim Morrissy, reviewing the anime for Anime News Network, was more positive, saying "Onimai is the best anime of the season." Morrissy strongly praised the narrative, humor, art, and animation production, particularly the work of series director Shingo Fujii, who previously worked on Precure. They also characterized the story as broadly relatable for its perceived theme of growing to accept significant personal changes. Sakugablog also mentioned Onimai multiple times in their Sakugabooru Animation Awards 2023 for Best Show, Best Animation Design, and other categories.

Popularity
In February 2023, fans of Onimai sent numerous gifts to the staff of Studio Bind, the production studio of the anime, which series director Shingo Fujii posted photos of in a tweet voicing thanks for the support.