On December 25, when it was snowing, middle school student Kazushige Sanda's body seal was broken by his classmate Shiori Fuyumura, making him look like Santa Claus. From that day forward he finds himself transforming into Santa whenever he wears red clothes. Later, Sanda discovers that he can change back by eating jellybeans. The reason why Fuyumura lifted the seal was that she hoped that Sanda would help find her missing classmate Ichie Ono, and also hoped that he would remind the society of Christmas.