Makunouchi Ippo is an ordinary high school student in Japan. Since he spends most of his time away from school helping his mother run the family business, he doesn't get to enjoy his younger years like most teenagers. Always a target for bullying at school (the family fishing business grants him a distinct odor), Ippo's life is one of hardship. One of these after-school bullying sessions turns Ippo's life around for the better, as he is saved by a boxer named Takamura. He decides to follow in Takamura's footsteps and train to become a boxer, giving his life direction and purpose. Ippo's path to perfecting his pugilistic prowess is just beginning...

Makunouchi Ippo is the new Featherweight champion of Japan and is now ready for his first title defense. His opponent, the former Jr. Featherweight champion and a medical student, Sanada Kazuki. In addition to this feud, Sanada is being coached by Kamogawa's former rival, Hama Dankichi. What makes things worse is that Sanada works at the same hospital where Kumi is a nurse at and everybody at the hospital wants Sanada to win. Not only does Ippo have to defend his title, he has to reclaim his love.

Kimura finally has his championship match. It takes place at the annual champion carnival. But now he must face the intense champion, Mashiba for the Junior Lightweight championship.