Oniichan wa Oshimai!


Onimai: I'm Now Your Sister!

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Alternative Titles

Synonyms: Onimai, Onii-chan is Done For
Japanese: お兄ちゃんはおしまい!
English: Onimai: I'm Now Your Sister!
More titles

Information

Type: TV
Episodes: 12
Status: Finished Airing
Aired: Jan 5, 2023 to Mar 23, 2023
Premiered: Winter 2023
Broadcast: Thursdays at 23:30 (JST)
Licensors: None found, add some
Studios: Studio Bind
Source: Manga
Genre: ComedyComedy
Themes: CGDCTCGDCT, Magical Sex ShiftMagical Sex Shift, SchoolSchool
Demographic: ShounenShounen
Duration: 23 min. per ep.
Rating: PG-13 - Teens 13 or older

Statistics

Score: 7.641 (scored by 8614886,148 users)
1 indicates a weighted score.
Ranked: #15422
2 based on the top anime page. Please note that 'Not yet aired' and 'R18+' titles are excluded.
Popularity: #1487
Members: 180,552
Favorites: 2,619

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7.64
Ranked #1542Popularity #1487Members 180,552
Add to My List
Episodes: /12

Synopsis

Self-professed "home security guard" Mahiro Oyama has not left his home in years, secluding himself in his room playing erotic visual novels. This depraved lifestyle causes his prodigious sister, Mihari, to worry about his well-being. In hopes of solving this problem, she devises a plan to rehabilitate him back to normalcy.

The first part of Mihari's plan is to concoct a medicine that changes her brother's biological constitution into a bona fide female, much to Mahiro's vehement dismay. Stuck in this predicament, Mahiro has no choice but to live out his life as a cute girl until the effect wears off—if it ever does.

[Written by MAL Rewrite]

Background

Oniichan wa Oshimai! was released on Blu-ray in two boxes from April 19, 2023, to June 21, 2023.

Characters & Voice Actors

Murosaki, Miyo

Supporting
Hioka, Natsumi
Japanese

Fujimi, Nemu

Supporting
Sakurai, Mia
Japanese

Leonardo

Supporting
Uchida, Yuuya
Japanese

Nagase, Miyako

Supporting
Oda, Karin
Japanese

Kitahara, Yuriko

Supporting
Nagae, Rika
Japanese

Staff

Hatakeyama, Takurou
Producer
Higashi, Mao
Assistant Producer


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Opening Theme

Preview
Spotify
Apple Music
Amazon Music
Youtube Music
"Iden Tei Tei Meltdown (アイデン貞貞メルトダウン)" by Enako feat. P-maru-sama. (P丸様。)

Episode Videos




Reviews

Jul 10, 2025
In the beginning I was worried if sex change motive will be annoying or boring for me - so after watching through the entire season - his sex change is only a hook and it lost it's importance after first few episodes. Mahiro is bona fide 100% girl in both looks and character that has zero behaviours that would even indicate her history as a male. At first I tried to explain how skittish she was by her being a NEET, but the longer the season went, the more obvious it became, that it is not the case.

So if we ignore sex change, what ...
Dec 18, 2024
Mixed Feelings
This Series does not adapt all the chapters and it adapts them in an odd order. This anime is fun and good but like horimiya just read the manga and get a fuller picture.

if you see this review after wards you only missed chapter 4(very trans), 19, and 23, along with most bonus chapters/pages

The anime itself is still good, with a bubbly art style that makes our cast look good. the humor in this is good for an anime but what makes this series any fun is watching the characters interact. The main cast are all so charming and distinct.
Dec 11, 2023
The premise is from the get-go that a man (older brother, true gamer nerd/enthusiast, recluse but ultimately harmless) wakes up having been turned into what looks like a pre-teen girl by his "mad scientist" sister, via a drug. In her room she has a manual on her desk which deetails how she wants to turn him into her little sister, meaning this is entirely deliberate with an agenda.

It SOUNDS like this should be a hilarious comedy to give a guy what he deserves in order to appreciate what being a girl or a woman is like, as punishment.
That's not at all what it is. ...

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Recent Forum Discussion

Poll: Oniichan wa Oshimai! Episode 12 Discussion ( 1 2 3 4 5 ... Last Page )
Stark700 - Mar 23, 2023
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