Yu Ayase's mother Subaru is gifted with beauty, athleticism, and intelligence, but Yu seems to have only inherited his mother's good looks and nothing else. When Yu is enrolled into a high-class school, he is entrusted to the care of his mother's friend, and moves to their house. There, he begins rooming with the three Mikadono sisters, who are all exceptionally talented in their own way, but have a weak side to them.