Joe Yabuki is an aimless young man who runs away from an orphanage with no money and no place to stay. He runs into a former boxing trainer, Danpei, who still has a strong passion for boxing. Danpei watches Joe fight and regains his desire to train future boxers. Joe, however, does not have any interest in boxing until he ends up in a juvenile prison where he meets Rikiishi, a former boxing prodigy. They quickly develop a rivalry and a newfound interest in boxing overcomes everybody in the prison, including Joe.