ONIMAI: I'm Now Your Sister! Gender-Bending Comedy Manga Gets TV Anime

Ichijinsha announced on Friday that Nekotofu's ONIMAI: I'm Now Your Sister! (Onii-chan wa Oshimai!) manga is inspiring a television anime starring Marika Kōno as protagonist Mahiro Oyama and Kaori Ishihara as Mahiro's sister Mihari Oyama. Ichijinsha is streaming a voiced motion comic video featuring the two voice actresses.

Shingo Fujii (Mushoku Tensei: Jobless Reincarnation episode 11 storyboards, director) is making his series directorial debut with the anime at Studio Bind. Michiko Yokote (Shirobako, Prison School Love All Play, Tsurune) is in charge of series scripts. Ryo Imamura (Mushoku Tensei: Jobless Reincarnation episode 11 animation director) is designing the characters. EGG FIRM is producing the series.

Kodansha Comics is publishing the manga digitally in English, and it describes the story:

Mahiro Oyama was just a normal erotic-game loving dude...until he woke up one morning as a woman! Turns out his mad-scientist little sister, Mihari, tried out one of her new experiments on him...with a disastrous outcome, as far as Mahiro's concerned! But Mihari is as determined to study him as he is determined to go back to his shut-in, game-playing life, and one thing's for sure...life is going to get a whole lot weirder from here on out!

The manga began as a self-published work by Nekotofu in 2017, which they published through pixiv and other places online. Nekotofu launched a regular serialization of the manga in Ichijinsha's Comic Rex magazine in April 2019. Ichijinsha will publish the manga's sixth compiled book volume and its second anthology volume on the same day on April 27. Kodansha Comics released the fifth volume in English on March 22.

Sources: ONIMAI: I'm Now Your Sister! anime's website, Mantan Web, Comic Natalie