One day, a mysterious package suddenly arrived at the home of Shiraishi Mamoru, a nursery school teacher. Inside was a mysterious furball creature named “Mofu". Mofu has become attached to Mamoru and does not leave him, so Mamoru decides to live with Mofu. Mofu changes into human form only when his master (Shiraishi) goes to bed, but if he is not loved by his master Mamoru within one year of his arrival in the form of a furball, he will disappear. Even if he disappears, he still wants to be with Mofu even if he is not loved...

After his parents died, Takada Shiro, who helps out at his grandmother's rice ball shop, is in love with his classmate and childhood friend Mitsui Hodaka. Shiro has decided to keep his secret feelings to himself for the rest of his life. Hodaka, who is unaware of this, spends his days fulfillingly with club activities and romance. He doesn't seem to notice Shiro's feelings at all. Shiro delivers rice balls from his shop to the stadium to congratulate Hodaka and the other members of the club who won the club's (fencing) match. While cleaning up, he notices that Hodaka is not in the waiting room. Hodaka is smoking behind the stadium, and Shiro sees him from the window. He thinks that if a passing teacher sees him, Hodaka's athletic career will be ruined, so he takes a surprising action on the spur of the moment...