Onimai: I’m Now Your Sister Vol.3 English Version Manga

Former shut-in Mahiro Oyama was transformed into a girl thanks to his little sister Mihari’s experimental drug… and he’s starting to like it! But his independent lifestyle is ruined when Mihari enrolls him in middle school! Can Mahiro survive middle school for a second time — and as a girl, to boot?! The brother-turned-beauty’s schoolgirl life begins here!