Tatsuya Kimura is beginning to feel left behind. With his friends Ippo Makunouchi and Mamoru Takamura holding the championship belt in their respective weight classes, Kimura's inability to become Japan's Junior Lightweight boxing champion eats away at him. Scheduled to fight with the current champion Ryo Mashiba, Kimura begins to train with Ippo's rival Ichirou Miyata, who previously suffered a crushing defeat from Mashiba's signature "Hitman" style of boxing.

But Mashiba has his own desire to hold onto the belt, hoping to soon shoot for the World title and secure financial stability for his sister Kumi. Will Kimura's overwhelming drive to prove his strength as a boxer overcome Mashiba's desperate wish to provide a better life for Kumi?