Joe Yabuki is a troubled young man who runs away from an orphanage. Wandering through the Tokyo slums, he meets former boxing trainer Danpei. Joe is later arrested and goes to a temporary jail where he fights Nishi, his future best friend and leader of a group of hooligans. He and Nishi then go to a juvenile prison miles away from Tokyo. There Joe meets Rikiishi, a former boxing prodigy, and a rivalry develops between them. They face each other in a match in which Rikiishi dominates Joe until the latter hits him with a cross-counter, resulting in both being knocked out. This inspires the other prison inmates to take up boxing. Joe and Rikiishi vow to fight again.

(Source: Wikipedia)

Teppei, brought up by his father in the mountains, is an energetic boy who is as tough as weeds and acts as free as a bird. His life changes completely when he enrolls in high school, the first school he has ever attended. Despite his eccentric behavior and being a constant source of troubles, he is soon recognized for his talent in sports-especially in Kendo (the Japanese swordplay art) - and becomes the school’s hero.