Oniichan wa Oshimai!
Type: Winter 2023 Anime
Plot Summary: 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!
Other name: Onimai: I'm Now Your Sister!, Onii-chan is Done For; お兄ちゃんはおしまい！