"Why do you need to forget him?" Tooru Naruse's life at university was mundane--until he met Izumi Wataya. Having fallen in love at first sight, he confesses his feelings for her, and she agrees to date him on one condition: He must promise never to fall in love with her. Thus, their pretend relationship begins--but Izumi cannot forget about her past love, and the attempt is short-lived. Hoping to learn who that person was and the reason behind her fleeting wistful expressions, Tooru reaches out to Izumi's best friend from high school, Maori Hino. However, maybe some things are best kept secret...