Immediately after Ryuuji Takane wins the Champion Carnival, he is challenged by the U.S. Junior Champion Black Shaft just before the World Tournament. Ryuuji, together with teammates Takeshi Kawai, Kazuki Shinatora, Ishimatsu Katori, and Superstar Jun Kenzaki, must prove to Shaft and the world that they are truly world‑class boxers before the tournament begins. Shaft, however, has assembled a formidable crew rather than simply recruiting fighters: a life‑timer criminal from Death Row, the leader of the Great Angels gang, a mysterious woman, and the Dark Emperor of the South. He also negotiates with Don Giuliano, the Italian Junior Champion.