Coy and self-conscious high school student Karin Karino never paid much attention to boys until she met Kiriya, a popular student from a nearby boys' school. Karin and Kiriya embark on a romantic journey despite Karin's classmate Yuka's best efforts to sabotage their relationship, but Karin soon learns that living happily ever after isn't on the curriculum when she becomes Kiriya's center of attention, as well as embittered Yuka's bull's-eye on her dartboard of hate.Karin and Kiriya's relationship is in jeopardy after a heated argument during Club Day at Kiriya's school. The following morning, Karin gets wind that her rival Yuka went on a group date with members of Kiriya's class, but Kiriya isn't talking. Is Kiriya cheating on her? But despite Karin and Kiriya's romance blowing hot and cold, their desire to spend Christmas together is overwhelming. Too bad Karin's father has them swaying to a melancholy holiday tune instead...