Baki Hanma fights a gang of 100 thugs; afterward, he is walked home by Detective Kido and his partner, who watched the fight. Baki then trains and thinks about what he should do to get stronger. Meanwhile, Kuriyagawa, the man who hired the thugs to fight Baki in order to test his strength, pays the gang's leader. Also, Baki watches a sparring match between Yuri Chakovsky, the international welterweight boxing champion, and Dinoy, Thailand's Muay Thai champion.

Baki spars with Yuri. Meanwhile, Kuriyagawa meets with Kaoru Hanayama, a gangster and renowned brawler, to set up a fight with Baki.

Baki meets his friend Ando in the woods and stays with him. While there, Baki adopts some of Ando's training techniques, and he camps alone on Yasha Rock, hoping to fight with the Yasha Ape.

Baki fights a rematch with the Yasha Ape.

After returning home, Baki learns that Yuri will be fighting for the heavyweight title, so he visits Yuri at his gym. Meanwhile, Kuriyagawa tells Hanayama that he can't fight Baki until Baki has fought Yuri, but Hanayama has other plans.

After being knocked down by Baki, Hanayama flies into a rage in his office; afterward, he visits his sick mother in the hospital. Also, Baki visits Yuri in the hospital before his rematch with Hanayama.

Baki and Hanayama continue to fight, and Hanayama's tattoo is explained.

Baki's dad, Yujiro, shows up after Baki's fight with Hanayama. After the story of how Yujiro met Baki's mother is told, Yujiro and Hanayama fight.

Baki explains to his mother why he fights, visits Hanayama in the hospital, and trains. After a brief encounter with Yujiro, they decide that they will fight in one month. Baki then meets Strydum, who tells him of a mercenary group in Hokkaido, and Baki decides to go there to defeat them.

Captured by the mercenaries as soon as he parachutes in, Baki must free himself and fight his way out. Meanwhile, an old friend warns Strydum of Gaia's fighting ability.

Baki fights Gaia.

Yujiro breaks into the Prime Minister's office to prove a point; Baki fights the swordsman Kurokawa; Yujiro forces the archer Kanemoto to shoot an arrow at him; Baki visits his mother after she is rejected by Yujiro.

All of Baki's friends show up to watch his fight with Yujiro and to help him warm up; meanwhile, Yujiro fights Gaia. Also, Hanayama opens up to Baki about his mother.

Baki fights Yujiro.

Detective Kido reflects upon his experiences with Baki, and Kuriyagawa tells Kido about Baki's relationship with his mother and his fight with Yujiro.

Anton Igari, an ex-wrestler, tells Tokugawa, an old man who runs an underground fighting circuit, about Baki and his recent global travels. In the narrative, Baki is seen training and fighting, and, while in Brazil, he visits a fighting master named Dixon. Learning of the circuit, Baki returns to Japan to meet with Tokugawa, and he fights Tokugawa's bodyguards to earn a chance to enter the circuit.

Flash forward three years: Baki is now the champion of the underground arena. Tokugawa meets with Orochi Doppo, a former champion of the arena, and asks him to enter his son Katsumi in the arena. Doppo finds Kato, a former student, at his dojo beating up his fighters, and he introduces Kato to the arena. Baki trains for a fight at the boarding house where he is staying, where Kozue, the daughter of the woman who owns the house, has a crush on him.

Baki fights Shinogi Kousho, a master of Cord-Cut Karate.

Kato spars with the fighters in Doppo's dojo; Kozue interferes with some bullies that are bothering Baki, which causes problems for her later; several fighters petition Tokugawa to be Baki's next opponent; Baki trains with Motobe Ito.

Baki fights Mount Toba, a professional wrestler.

Yujiro shows up after Baki's fight and knocks him out, and Doppo challenges Yujiro to a fight. After watching Doppo spar with his students, Baki spars with him. Yujiro starts a fight with a group of boxers at their gym, and he fights with Motobe Izo and Baki's next opponent is revealed.

Dr. Shinogi Kureha reveals to his brother, the Cord-Cutter, why he is fighting Baki; Doppo and Yujiro fight.

The fight between Doppo and Yujiro continues; after Dr. Shinogi Kureha performs a medical miracle, he demonstrates his physical abilities to the crowd; one of Kureha's former patients visits Baki.

Baki fights Dr. Shinogi Kureha.