Sakura-sou no Pet na Kanojo

Sakura Dormitory is a dorm of the high school affiliated with Suimei University of the Arts (often shortened as Suiko), which hosts the strangest, trouble-making students. After being kicked out of the normal dorm for keeping a stray cat, Kanda Sorata moves into Sakura Dormitory. As he starts to get used to the life in the dorm, Shiina Mashiro, a world famous artist who cannot even take care of her daily life, moves in. Sorata is forced to become Mashiro's handler. The story is about their daily life as well as mental growth.

[Edited from Wikipedia]