In a chaotic and violent yakuza underworld, a sadistic enforcer named Kakihara seeks out his missing boss, Anjo, who has vanished with a fortune in gang money. Kakihara's brutal methods lead him through a web of underlings and miscreants, each encounter revealing more about the gruesome power struggles within the criminal organization. Meanwhile, an unassuming young man named Ichi, manipulated by his mysterious handler Jijii, is unleashed as a weapon of destruction. Tormented by suppressed memories and psychological traumas, Ichi’s uncontrollable violence becomes a force that shakes the very foundations of the yakuza world.

As Kakihara's search intensifies, he learns about Ichi—a killer with extraordinary martial prowess but a fragile, childlike psyche riddled with guilt and confusion. Desiring a worthy adversary to quench his own masochistic thirst, Kakihara becomes obsessed with finding Ichi. The narrative delves deeper into their backgrounds, juxtaposing Kakihara’s fearless yet sadistic persona against Ichi's tragic and unpredictable nature. The tension builds as paths converge amid a backdrop of ruthless ambition, manipulation, and the quest for ultimate power, setting the stage for an inevitable and brutal confrontation.