After inadvertently killing Toru Rikiishi in the ring, Joe Yabuki finds himself aimlessly wandering the city at night, when he comes across a fight between Wolf Kanagushi, his former opponent who has become a Yakuza muscleman and Goromaki Gondo, a henchman from an opposing Yakuza group.

After a long absence, Joe returns to Tange Gym where he is welcomed with open arms. He pays his respect at Rikiishi's grave and swears to return to the ring. Even after being away for several months, Joe proves his punches are still as powerful as ever in his spar against Nishi. The bell to Joe's first comeback match echoes through the hall.

Joe proves his comeback K.O. victory is no fluke. With his powerful punches, Joe sends his opponents to the hospital one after another. The rival boxing club owners see Joe as a serious threat and band together to get rid of him.

Joe, a fledgling boxer, is unfairly matched up against Tiger Ozaki, the National Bantamweight Champion. Despite the odds, Joe sees it as an opportunity to instantly climb to the top and is confident he can defeat Tiger Ozaki. However, right before the bout, a member of Tiger Ozaki's team reveals they have discovered Joe's weakness.

After a humiliating defeat against Tiger Ozaki, Joe agrees to another bout despite Danpei's protests. Under Tiger Ozaki's guidance, Ryu Harajima, Joe's opponent takes advantage of Joe's weakness in the ring. To prove them wrong, Joe unleashes a punch to Harajima's temple, the same punch that killed Toru Rikiishi. However, an unexpected physical reaction suddenly overwhelms Joe.

Despite learning his inability to strike his opponent in the temple is psychological, Joe is undeterred and trains for his upcoming fight against Koji Nango. Joe climbs into the ring while Carlos Rivera, the world's No. 6 bantamweight boxer from Venezuela, watches from the ringside.

Without a club willing to organize a bout against him, Joe's career seems over for certain. Even Danpei says, "Joe Yabuki, the boxer is dead" and urges him to retire. Unable to accept his career may be over, Joe is at a loss. Then, he receives an invitation from Yoko to see Carlos Rivera's fight. What kind of man and boxer is Carlos Rivera?

Danpei closes the gym and disappears to make Joe realize that his career is over. However, Joe refuses to give up boxing and continues to train. He catches Carlos Rivera's second match on TV and realizes what he saw during Carlos' first match was no trick of the eye. He visits the Shiraki Gym where Carlos is training and offers to be his sparring partner.

Joe is slowly released from the ghost of Toru Rikiishi during his heated spar against Carlos. After realizing Joe can punch his opponent's temple again, Danpei reopens the gym and the two go see Carlos's bout. Before his bout against Tiger Ozaki, Carlos searches Joe out of the crowd and predicts a one round K.O. victory.

It's Christmas and the mood is merry in the slums. Snow begins to fall, as Carlos and Joe's fire burn quietly inside of them. In the snow-covered park, Joe challenges Carlos to a fight to settle who is best. However, Carlos has another plan.

As the New Year's Eve bell counts down the passing year, Joe and Carlos' bout kick off with the sound of the boxing bell. Joe and Carlos put on a heated and breathtaking fight. However, Joe is unable to land his forte, the cross-counter. With no other option, Joe makes a daring attack by the ropes, but will it be enough to defeat Carlos?

Joe loses consciousness after being hit with Carlos' powerful uppercut. However, he refuses to go down without spending every last ounce of his strength. Carlos' "invincible punch" mercilessly rains down on Joe. Their fierce fight continues, as both boxers fight with all their might. Who will be victorious?

With Joe's bout against Carlos now over, Joe, Danpei and the people from the neighborhood are busy organizing Nishi's retirement party. However, unbeknownst to everyone, Nishi was struggling to accept that he could no longer physically box. At his retirement party, Nishi asks Joe to spar with him one last time.

Joe visits the Shiraki Gym to pick up his prize money. There, he learns the World Champion had defeated Carlos. Joe also learns Carlos had become incapacitated as a boxer and that he was to blame. Seeing the pain in Joe's eyes, Noriko suggests he quit boxing.

Without a boxing club willing to organize a bout against Joe, Danpei visits Yoko for help. However, instead of organizing a bout against a Japanese boxer, she chooses Usman Somkit, the Oriental and Pacific Boxing Federation's No. 5 boxer from Thailand as his opponent. With Carlos still on his mind, Joe climbs into the ring...

With a lightening fast victory against Usman Somkit, all eyes are back on Joe. Meanwhile, Joe finally gets the opportunity to watch the gut-wrenching bout between Carlos and Jose Mendoza, the World Bantamweight Champion. Joe vows to avenge Carlos, but before he can challenge Jose he must defeat Tarny Aronzo, the OPBF's No. 3 boxer from the Philippines and climb the ranks.

Joe steps onto the gym scale and makes an unwelcome discovery. Meanwhile, Kanto TV has announced their exclusive broadcasting rights to all of Joe's bouts in Japan. At the announcement party, Joe notices an unlikely man standing amongst the crowd. Who is the uninvited guest and what is his objective?

Joe is eager to take on Yongbi Kim, the OPBF Bantamweight Champion, but according to Danpei, Kim is avoiding Joe because he's afraid of him. When in fact, Kim is eager to take on Joe, as well. Danpei has his reasons to want to avoid a bout between the two and is willing to cast a web of lies in order to keep Joe from finding out.

With Joe and Kim's Championship match now confirmed, Yoko sends Suga to South Korea to find out Kim's mysterious past, while Kim's manager secretly gathers information about Joe. Joe and Danpei watch Kim's exhibition match against a boxer, who is two weight classes above him. As the fight unfolds, a cold chill runs down Joe and Danpei's spine.

Despite the match being three weeks away, Joe is struggling to lose weight. Desperate to lose weight, he turns the gym into a dangerously hot sauna. After almost passing out, Danpei urges Joe to stop his dangerous weight loss attempts. Determined to stay in the bantamweight class and without Danpei willing to support him, Joe holes himself up in the attic room and refuses to eat...

With Danpei vehemently against Joe's dangerous weight loss, Joe leaves the Tange Gym. He visits the Shiraki Gym and locks himself up in the very same room where Toru Rikiishi once starved himself, so he could fight Joe. Joe's thirst and hunger reaches its peak and he goes into a wild rage as though he were mad. Unable to watch any longer, Danpei relents and offers to help Joe.

After a grueling weight loss regimen, Joe finally loses enough weight to stay in the bantamweight class. However, during the official weigh-in, Joe discovers he is actually over the weight limit and that Danpei had altered the scale back at the gym. With only a few hours left until the final weigh-in, Joe resorts to drastic measures knowing full well that it might kill him.

With the final weigh-in now over, Danpei brings Joe to a restaurant so he can enjoy a small meal before his match. Kim, who happened to come to the same restaurant, asks Joe if he could join him. Seated across from Joe, Kim begins to tell him about his past. What horrifying truth about his past will Kim reveal to Joe?

Kim's manager confidently predicts Kim's victory during the pre-fight press interview. Danpei and Nishi encourage Joe in the locker room, but Joe is not his usual self. Unsurprisingly, Kim dominates the fight and Joe can only defend himself. However, no matter how hard Kim knocks him down, Joe continues to get up. Why does Joe continue to get up in such a hopeless fight?

Joe has fought beyond his limit, yet he refuses to go down. Unable to comprehend how Joe can continue to fight, Kim slowly becomes unhinged and resorts to using his deadly technique known as Chom-Chom.

With is victory over Kim, Joe is now the OPBF Champion. His next goal is to defeat Jose Mendoza, the World Bantamweight Champion who crushed Carlos. Then one day, Joe learns about a Japanese boxer, who once fought Jose and decides to pay him a visit.

Joe happens to run into Wolf Kanagushi, a former boxer at a pachinko parlor. He is relieved to learn that Wolf is now working as a trainer at a boxing gym, and is no longer a Yakuza muscleman. Wolf tells Joe about the financial struggles the gym is facing

As the OPBF Champion, Joe’s first title defense match has been confirmed in Hawaii. Not wanting to go all the way to Hawaii, Joe is reluctant about the fight, but quickly changes his mind when he learns Jose is also having a bout in Hawaii.

Knowing Jose is watching from the ringside, Joe predicts a two round K.O. victory. However, Joe quickly realizes that defeating his Hawaiian challenger will be harder than he originally thought.

After successfully defending his title, Joe is eager to challenge Jose more than ever. Then one day, Yoko invites Joe to spend some time with Jose and his family on a horse ranch. Joe finally gets an opportunity to question Jose.

As the OPBF Champion and world champion hopeful, it seems everyone wants a piece of Joe now. Meanwhile, the new Tange Gym that’s been under construction is finally complete and Danpei accepts several new aspiring boxers as apprentices.

Jose, the WBC World Champion must fight Harold Gomez, the WBA World Champion in a unification bout to determine the true World Bantamweight Champion. Meanwhile, Joe, the OPBF Champion and now the World’s No. 5 boxer, must defeat Leon Smiley.

Leon dominates the fight and Joe is on defense. However, Leon’s underhanded tactics light a fire inside Joe and the fight quickly becomes a fierce and tightly contested battle. With no knockout punch from either side, the winner is determined by points.

Jose, the WBC World Champion and Gomez, the WBA World Champion will fight head to head to determine the true World Bantamweight Champion. Joe, who has won his right to challenge the winner of the unification bout, flies to Las Vegas to see Jose and Gomez’

Yoko, who feels Joe has lost his wildness within, offers to give up her exclusive rights to Jose’s fights in Japan, under the condition that Joe fights one last bout before his title match against Jose.

Harimau, a wild beast-like man who grew up deep in the Malaysian jungle has been confirmed as Joe’s challenger. Yoko brings Harimau to the Tange Club to introduce him to Joe, but Joe reiterates his displeasure about having to fight.

Joe is humiliatingly caught off guard by Harimau, not once, but twice. Admitting he’s lost his street fighting instincts, Joe asks Goromaki Gondo, a Yakuza henchman for his help. Invited by Joe, Gondo and his subordinates show up at the Tange Gym.

The bout between Joe, the Brawler and Harimau, the Wild Beast begins. At first, Joe struggles to keep up with Harimau’s agility and speed. However, Harimau proves to be no match against Joe, who has regained his instincts as a former street fighter.

Yoko arranges Carlos to be admitted into a hospice to recuperate. However, Dr. Kinninski, the world’s leading authority on punch-drunk syndrome delivers the devastating diagnoses that Carlos is suffering from a severe case of punch-drunk syndrome.

Noriko and Nishi are engaged. Joe is happy from the bottom of his heart to see his long-time pal marry his dream girl. Meanwhile, Jose arrives in Japan just two days after their bout has been officially confirmed.

Noriko and Nishi are engaged. Joe is happy from the bottom of his heart to see his long-time pal marry his dream girl. Meanwhile, Jose arrives in Japan just two days after their bout has been officially confirmed.

After noticing Joe might also be suffering from punch-drunk syndrome, Yoko asks Dr. Kinninski for his professional opinion. Dr. Kinninski is reluctant to give a concrete diagnosis without examining Joe.

In order to avoid Danpei finding out about his health, Joe decides to train with Nishi and Danpei at a mountain lodge, far away from Yoko. Desperate to tell Joe about his health, Yoko tracks down Joe and visits the mountain lodge.

On the day of the title match, Yoko finally tracks down Joe in his locker room and urges him to cancel the fight before he ends up like Carlos. She learns Joe is well aware of what is happening to his body, and that he is going to fight Jose regardless.

Joe and Jose finally face off in the ring. With his impenetrable defense, Jose dodges Joe’s attacks while hitting him with his own punches. After receiving countless blows and unable to land a meaningful punch against Jose.

Jose is rattled by Joe’s sudden comeback, but quickly realizes Joe is no longer able to see out of his right eye, due to the effects of punch-drunk syndrome. Jose moves to Joe’s blind spot and batters him with his punches.

No one doubts Jose’s victory, but something begins to change. While, Jose is unable to knockout Joe completely, Joe masters Jose’s corkscrew punch and continues to fight with a blatant disregard for his life.