Just before her senior, Yoshihiko, departed for college, Kana Orikura finally mustered the courage to confess her feelings to him. After sharing their first kiss, the pair agreed to start dating—a dream realized for Kana. From that initial moment, however, Kana and Yoshihiko have faced difficulties in their relationship, leaving Kana feeling isolated and downcast. Yet the situation shifts unexpectedly when Shougo Hayakawa, the young and handsome teacher assigned to Kana's class, begins residing in her home! Will Kana betray Yoshihiko for this new rival, or stay faithful to the man who took her first kiss?