Taniguchi Tomoo, Tomorowo Taguchi, is a married salaryman with a wife and a son named Minori,Keinosuke Tomioka, but he has no memories before his eighth birthday. On a routine outing, two skinheads— the Big Skinhead Hideaki Tezuka and a younger, ruthless companion—the Young Skinhead Tomoo Asada—use an injection gun to sap him with an unknown substance and kidnap the boy. After a tense chase, the assailants retreat, leaving the child unharmed, yet the encounter shakes Taniguchi to his core. In the wake of the incident, he discovers an astonishing surge of strength he cannot explain, a force that seems to surge from inside and reshape his body in ways he does not yet understand.
The danger intensifies when Minori is taken again from their home. Taniguchi pursues the kidnapper to a rooftop, where the fight nearly ends in tragedy; the kidnapper hurls Minori off the ledge, and in a furious, desperate response, Taniguchi’s arm morphs into a cannon and fires. The shot is fatal not to the target alone, but to Minori, who is caught in the crossfire. The sight leaves Taniguchi and his wife in a state of stupefied horror as the kidnapper slips away. The couple is left to grapple with the terrifying cost of the power they now know lurks within him, a power that overrides all norms of human limit.
Behind the scenes, the abductors regroup at a hidden lair where their cohorts perform brutal weight-lifting rituals. They meet a Mad Scientist Torauemon Utazawa and hand over the injection gun, while the leader, Yatsu—the man many know as “The Metal Fetishist” or “The Guy”—declares that their ultimate aim is destruction, with every cult member seeking the same warped transformation. The Mad Scientist begins to manipulate Taniguchi’s memories, accelerating his metamorphosis from man into something more machine than flesh. Yatsu’s plan is stark and chilling: every member will inject themselves and become an instrument of their twisted godhood. In a brutal moment, Yatsu kills the Mad Scientist, believing the weapon is ready, and the danger escalates as the skinheads begin their full transformation.
Meanwhile, Taniguchi’s home life grows more fragile. Kana, his wife—Nobu Kanaoka—discovers a startling truth: the injection he received didn’t truly modify him; instead, the power was always there, blocked by a pocket organizer that somehow shielded him. When she returns home in a panic, she is promptly kidnapped by the cult as well, leaving Taniguchi to confront the full scope of the threat alone. As the cult’s influence spreads, Yatsu speaks openly about what awaits him and his followers, and Taniguchi’s resolve hardens into a weaponized certainty.
Tomoo eventually tracks the cult to its hideout and confronts Yatsu. The confrontation is brutal, and in a shocking moment, Kana is seemingly killed, a wound that shatters whatever remaining humanity Taniguchi clings to. This catastrophic loss triggers a complete transformation; his body becomes a fusion of flesh and metal, more machine than man, and he becomes a formidable force against his former allies. In a desperate gambit, Yatsu shoots a cable into Taniguchi, attempting to bind their minds, and the two brothers collide in a climactic struggle.
The truth behind their origins comes to light: Tomoo and Yatsu are biological brothers, the sons of a father who sought to create the perfect human weapon. Their father trained them with firearms that would become a part of their bodies, and in a harrowing, ritualistic revelation, the boys witness their father kill their mother in a grotesque ritual that involved the mother sucking on a gun. This brutal memory explains the brothers’ repressed past and how violence and power fused with memory to birth their monstrous identities.
Tomoo and Yatsu merge into a colossal, hybrid being—part human, part machine—who then fuses with the cultists to form an armored vehicle that courses through a ruined city. Kana clings to the exterior as it rumbles along the streets, held in a perilous grip between humanity and the weaponized future that forged them.
Time passes in a harsh, quiet way. Kana, Tomoo—still in a battered human form—and his son walk through the desolate ruins of a city. The air feels oddly peaceful in the aftermath, and Kana’s quiet observation that the place is now so quiet and serene lingers as a stark contrast to the violence that preceded it. The film closes on this uneasy note: a city scarred by its own awakening, where the remnants of a family and a man who became a machine search for a fragile calm amid the wreckage.
