The protagonist is a high school boy, Kazunari, who works part-time as a newspaper delivery man to support his family. Having lost his father two years ago, he has been busy with school, part-time work, and housework. One day, his mother is involved in a traffic accident and is hospitalized. This puts an even bigger strain on the family's finances, and Kazunari begs to be allowed to work as an employee at his part-time job. However, someone at his workplace suggests that he became a keirin racer, something he had no connection to before.