Seiji Utsumi was satisfied with just gazing at his beloved Shou-sempai from afar. But when his classmate, Yuki Kurokawa, finds out about his crush, she pushes him to take action, and his one-sided love starts moving rapidly! Kurokawa receives a letter from her ex-boyfriend, Toru, which prompts a fight between her and Utsumi. After Kurokawa brings Utsumi a present and cake for his birthday, the ill-will melts away, and the two find themselves closer than before. But as things heat up, Utsumi finds that Kurokawa's past is still closer than he thought...