Onimai: I'm Now Your Sister!

is a Japanese manga series written and illustrated by Nekotofu. It is 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 has been announced.

Plot
Mahiro Oyama is an otaku living with his scientist younger sister Mihari. One day he wakes up as woman, a result of one of Mihari's experiments. Mahiro must now learn to live as a woman, all while making friends in his new school.