Oniichan ha Oshimai - Mihari is adorable, but Momiji's route is also...
Oniichan wa Oshimai! (Onimai: I'm Now Your Sister!) is a comedy and slice-of-life manga series written and illustrated by Nekotofu. With 10 volumes currently available, the series first caught my attention when it received an anime adaptation. Since then, I have started reading the manga and am currently on volume 7.
The story follows Mahiro Oyama, an otaku who lives with his younger sister, Mihari, who is a scientist. He is the definition of a failure: he does not work, and he spends his days surfing the web, playing games, and complaining. No information is immediately provided as to why he ended up this way.
The story shifts immediately when his sister slips a secret potion into his drink, transforming him into a young girl. This begins Mihari's attempt to reform her brother by making him behave like a middle school girl and socialize with other girls at school.
Sounds crazy? It definitely is, but it is also a lot of fun. The story is told through a comedic lens, with Mihari acting as the anchor who keeps Mahiro motivated to slowly return to a normal life. Of course, "normal" in this case means transforming into a beautiful girl and attending school as one.
The narrative is very lighthearted and usually centers on a specific new experience Mahiro faces in his life as a female, along with all the comedy that results from it. While there is an overarching plot about Mahiro wanting to return to being male, progress on that front is quite slow.
The main characters are:
Mahiro Oyama: The protagonist of the story. He starts with a typical otaku personality, but as the transformation continues, he begins to adopt more feminine traits to the point where he becomes worried about it himself. He is conflicted about whether or not he truly wants to return to being male.
Mihari Oyama: Mahiro’s younger sister, though she acts like the only responsible adult in the room. This is true at least when she isn't performing crazy experiments on her brother. Despite her young age, she is already a university student because her abilities allowed her to skip multiple grades.
Kaede Hozuki: A close friend of Mihari from middle school. She is a "gal" who is skilled at cooking and using cosmetics, and she loves practicing her makeup skills on Mahiro. Although she has a trendy look, she possesses a domestic aura that makes her feel more like a mother figure than anything else.
Momiji Hozuki: Kaede’s younger sister. She is a tomboy who starts as Mahiro’s friend but gradually develops feelings for her. I am not sure if this should be called yuri given the situation, but I will stick with the term since Momiji is unaware of Mahiro’s true identity.
Asahi Ouka: Introduced as a friend and classmate of Momiji. She is an energetic, somewhat simple-minded character who is genuine and forward, though she struggles with academics. She frequently hangs out with Momiji and Miyo at Mahiro’s house.
Miyo Murosaki: A friend of Momiji and my personal favorite character in the manga. Joking aside, she loves fantasizing about yuri relationships between her friends, and it is entertaining to see the situations she imagines. She has a complex about her body because she is much more physically mature than her classmates.
My overall favorite is definitely Mihari because of the humor she brings to the story and her deep affection for Mahiro. She set everything in motion and is always the person Mahiro can rely on when things go wrong. A close second is Momiji, who is clearly the main heroine regarding the romantic elements.
Onimai is an extremely entertaining series and something I can easily recommend to anyone looking for pure comedy with some yuri undertones. I plan to catch up with the series in the coming weeks, so expect another post soon.
