ONIMAI: I'm Now Your Sister!

Mahiro Oyama was your average NEET, content to spend his days gaming and living off his younger sister, Mihari. That is, until Mihari, a self-proclaimed mad scientist, decides her brother makes the perfect test subject for one of her experimental new drugs. The result? Mahiro wakes up to find himself transformed from a slovenly shut-in into an adorable young girl! Now navigating the bewildering world of middle school and girlhood, Mahiro must contend with everything from new friendships to unfamiliar bodily changes, all while trying to keep his true identity a secret. With Mihari observing his every move and a new circle of friends to impress, can Mahiro truly embrace his unexpected new life, or will he forever pine for his past as a big brother?

✦ AI-drafted summary