21st century

A boy is initially overjoyed at the news of him having an older sister, due to his father remarrying to a woman who has a daughter. That is, until he finds out that his new sister is actually his school's strict PE teacher, Shina. With his father going off to live with his new wife, the boy will live alone with his new sister. In their new life together, the boy finds out that Shina at home is completely different from Shina at work: clumsy, scared of insects, and kind.

April! Sawaya Doji's college life at his dream school of Seio University starts with an encounter with the beautiful Kaede Hoshimi during the club recruiting fair. Sawaya believes that if he goes to Tokyo... if he joins a university... if he joins a club, he can get a girlfriend! It's a great way to meet new people, but what kind of club has he gotten himself into?