Due to an error, newly-enrolled Otorinashi Academy student Yuuki Kagami is assigned a room in the girls dormitory, even though Yuuki is a guy. Since none of the other rooms for guys are available, he ends up having share the room with Ayana Kakinozaka, his beautiful but ditzy homeroom teacher who made the mistake in the first place. To avoid getting kicked out of the school for being a boy in a girls dormitory, Yuuki has to share his room with Ayana, his self-proclaimed guardian, and cross-dress whenever he is outside his room and when he is not in his classes. Yuuki meets several other characters in Otorinashi Academy, the first being Risa Takabane, whom he accidentally walks into, leaving a bad impression. Risa finds out about his situation, but decides to keep it a secret, on the condition he becomes her slave. Over the course of the series, he encounters other girls including student council president Patricia Bepouin, most of whom have a romantic or at the least a strong sexual attraction to him.