In the corporate underworld of Japan, wealthy conglomerates resolve massive business disputes not through courts, but through gladiator-style combat known as Kengan matches. These high-stakes bouts are funded by ruthless CEOs who hire elite fighters to protect their economic empires. Nogi Hideki, a cunning executive for Nogi Group, discovers Tokita Ohma, a ferocious and battle-obsessed martial artist nicknamed "The Ashura." After Ohma brutally defeats Nogi’s seasoned fighter in a street brawl, Nogi enters him into the Kengan Association, setting the stage for the ultimate tournament.Meanwhile, Kazuo Yamashita, a stressed and timid middle-aged salaryman working for Nogi, is suddenly thrust into the role of Ohma’s manager. Initially terrified of Ohma’s volatile nature, Yamashita forms a complex, paternal bond with the fighter. Yamashita soon learns that Ohma is haunted by flashbacks of his shadowy master, Tokita Niko, and is driven by an intense desire to find and defeat the man who killed him.The main narrative revolves around the Annihilation Tournament, a colossal, winner-take-all competition held on a private island to determine the new Chairman of the Kengan Association. As dozens of deadly fighters—ranging from deadly assassins and sumo grand champions to genetic freaks and lethal practitioners of esoteric martial arts—clash in the arena, the stakes escalate dramatically.
Behind the scenes, a massive conspiracy unfolds. Hayami Katsumasa, a treacherous conglomerate leader, orchestrates a violent coup, plotting to overthrow the current administration and seize absolute control of
the organization using an army of armed mercenaries and brainwashed fighters.As the tournament progresses, Ohma’s body begins to fail him. He frequently uses the "Advance," a dangerous technique that forces his heart to pump at superhuman speeds, granting him devastating power at the cost of severe internal damage and memory loss. Despite his failing health and agonizing physical toll, Ohma battles through brutal, near-death matches against formidable opponents like Raian of the psychopathic Kure clan, and Wakatsuki Takeshi, a genetic powerhouse with muscles dense as steel.In the chaotic climax, as Hayami’s coup plunges the tournament island into bloody warfare, the fighters unite to defend the association against the corporate terrorists. Amidst the gunfire and betrayal, Ohma reaches the tournament finals to face Kuroki Gensai, the stoic master of the Kaiwan style. In a grueling, deeply emotional final battle, Ohma pushes his broken body past its absolute limits, finally making peace with Niko’s memory and letting go of his self-destructive rage. Though Ohma succumbs to his injuries and peacefully passes away immediately following the tournament's conclusion, his fierce spirit, his unbreakable bond with Yamashita, and the unforgettable legacy of the Ashura forever alter the landscape of the Kengan Association.