Keitaro Urashima is trying for the 3rd time to get into Tokyo University, the most prestigious university in Japan. Because of a promise he made to a girl when they were children. His parents, who only see him as a loafer, are constantly nagging him. So when his grandmother invites him to visit at her girls' dorm, the Hinata Apartments, he becomes the manager of the apartment and attempts to pass the university entrance exam. At the Hinata apartment, Keitaro meets a girl, Naru Narusegawa who is also studying to pass the university entrance exam. Naru, Keitaro, and Mutsumi take the entrance exam for Tokyo University again. However, Keitaro thinks he doesn't pass the exam. So, Keitaro disappears before the results of the exam are announced. Naru acts like she doesn't care. But, Naru sets off to rescue him as soon as discovering that Keitaro is on a tropical island.