What is ONIMAI: I’m Now Your Sister!?#
If you are looking for a series that blends science fiction experiments with the struggles of a shut-in lifestyle, ONIMAI: I’m Now Your Sister! (also known as Onii-chan wa Oshimai!) is a wild ride. The story follows Mahiro Oyama, a man obsessed with erotic games and staying indoors, whose life takes a drastic turn when his younger sister, Mihari, uses him as a test subject for one of her scientific experiments.
Mahiro wakes up as a girl, and the series explores the resulting chaos as Mihari studies her brother’s transformation while Mahiro desperately tries to find his way back to his old life. It is a quirky, weird, and comedic look at identity and familial bonds.
If you want to start watching this transformation tale, you can watch the anime on Prime Video.
Is the anime really finished?#
When deciding whether to commit to a series, the biggest question is often whether the story reaches a satisfying conclusion. ONIMAI: I’m Now Your Sister! is an adaptation of a manga that began serialization on pixiv in February 2017. Because the anime is based on this pre-existing source material, viewers who watch only the anime may find themselves wanting more of the story.
For those who crave a deeper dive or want to see how Mahiro’s journey progresses beyond the televised episodes, continuing with the manga is the best way to ensure you get the full experience. You can buy the manga here to see where the story goes.
Who is this anime for?#
This series is best suited for fans of comedy and “slice-of-life” stories with a supernatural or scientific twist. Its primary appeal lies in its absurdity—specifically the “gender-bender” trope—and the dynamic between the determined scientist sister and her reluctant, transformed brother.
If you enjoy themes of social anxiety, gaming culture, and the humorous complications of unexpected life changes, this is a great pick. While you’re enjoying the show, why not pick up some ONIMAI merchandise to celebrate your new favorite series?
Recommended Watch and Read Order#
Depending on how much of the story you want to consume and in what format, there are a few ways to approach this series. For detailed connections between the versions, please refer to the relationship tree below.
The Release Order#
If you prefer to experience the story as it was presented to the general public, start with the anime, which debuted on January 5, 2023. This is the most accessible way to enter the world of Mahiro and Mihari.
The Completionist Order#
For those who want every detail and the original vision of the creator, we recommend starting with the manga (2017) before moving to the anime adaptation. This allows you to appreciate the source material that paved the way for the animation.
For Source Material Fans#
If you don’t mind jumping between mediums, you can watch the anime first for the high-quality visuals and then pick up the manga to continue the plot from where the anime leaves off.
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ONIMAI: I'm Now Your Sister! • manga • 2017-02-25 (serialized on pixiv)
└─(adaptation)→ ONIMAI: I'm Now Your Sister! • anime • 2023-01-05
