Joe is a teenage orphan living in the slums of the Doya streets. He encounters Danpei, a homeless alcoholic and former boxing coach, who recognizes Joe’s natural talent and agrees to train him. When Joe is sent to a harsh juvenile detention center for petty crimes, he meets Rikiishi, who becomes his boxing rival. Danpei visits the facility to help Joe train for a fight against Rikiishi. Although Joe resolves to pursue boxing seriously, Danpei cannot obtain a coaching license because of his reputation as a drunk.