Triangle Heart (2000)

Based on a game by ivory (Janis). Makihara Kousuke works as a substitute janitor of woman dormitory, Sazanami So, while the regular janitor, who is his aunt, travels abroad. The contract term is almost over, but he has one thing worried about. Among the member of the dormitory, only Jinnai Mio doesn't open out to him and doesn't try to eat his dishes. Then, he makes the former janitor's favourite dish to let her eat.