Otome Domain The Animation.

Due to his grandmother's death, the protagonist is all alone in this world. The daughter of a wealthy family, a girl his age who is also an administrator at an all-girls school, offers him a helping hand and a fresh start. With nowhere else to go, he dons a girl's uniform and begins living in the girls' dorm. But the ladies he's living with are all a little off. "Where'd I put my panties... I guess I'll have to go without them today..." "I'll get some for you immediately! Wouldn't there be trouble if you went out like that!?" His new life with the academy's residents was supposed to be a fresh start, but who's taking care of whom!?