Hoshino Wataru

Wataru is a childhood friend of Umi Hayama. He cares about everybody who lives in Tsugumi Dormitory. He tries to help everybody who is depressed.

He used to live with his grandparents. In the beginning of the story, Wataru lied to his grandparents that he is living in the boys' dorm at the Tsugumi dormitory, but Wataru was the only person that was in the boys dorm, so the school revoked the boys' dormitory last year. Now, the girls' dorm is where everyone can live (including guys) that is from Takamidsuka senior high school. His grandparents later on figure out that Wataru lied to them.

Edited from Wikipedia