A metal fetishist enters his Tokyo hideout, which is full of rusted parts and photos of famous athletes. He cuts open his thigh and thrusts a large metal rod into the wound. Later, he unwraps the wound to discover it rotting and covered with maggots. He exits the hideout, running down the street and screaming until he is hit by a passing car.
A businessman day-dreams, tormented by visions of metal and industrial machinery. While shaving in his apartment, he notices a metal spike protruding from his cheek that spurts blood when he touches it. He speaks to his girlfriend on the phone, she cannot stop thinking about "the incident".
The businessman is on his way to work. On the platform he sits next to a woman wearing glasses. She notices an abomination of flesh and metal on the ground. She pokes it with a pen and is quickly overcome by it, becoming a zombie-like puppet of the fetishist. The businessman flees in terror to a toilet and is briefly able to escape by stabbing the woman with a pen and then running and hiding in a workshop. She soon finds him but he is able to defeat her with his growing metal powers.
The businessman dreams of his girlfriend, who dances erotically with a hose-like phallus before sodomizing him with it. Back in his apartment, the businessman is horrified to see his metal transformation is accelerating. He and his girlfriend have sex. Afterwards, his girlfriend eats suggestively, each interaction with the food accompanied by the screeching sounds of metal. Suddenly the businessman's penis is transformed into a large metal drill and he soon loses control, attacking his girlfriend. She stabs him in the neck with a kitchen knife and believing she has killed him, commits suicide by impaling herself on his drill. The businessman awakens and realizes what has happened, while elsewhere the fetishist laughs maniacally.
The businessman's transformation into "the Iron Man" is complete. He receives a phone call from the fetishist, who tells the Iron Man that he is coming for him. It is revealed that the businessman and his girlfriend are the ones that struck the fetishist with their car, disposing of the body in the woods and then having sex up against a tree. Upon realizing this, the Iron Man attempts to electrocute himself but it only serves to stimulate him further.
The fetishist makes his way to the Iron Man's apartment, destroying all metal in his wake. He possesses the body of the dead girlfriend and attacks the Iron Man, eventually emerging in his true form. The fetishist easily overpowers the Iron Man and shows him a post-apocalyptic vision of the "New World" - the Earth consumed by metal. A fight ensues and the fetishist chases the Iron Man across the city, before being briefly incapacitated by a vision from childhood where he is repeatedly beaten by a vagrant with a metal rod.
The Iron Man rests in an old factory, but the fetishist appears and attacks him. By now the Iron Man has transformed into an unstoppable mass and absorbs the fetishist's attack, combining the two into a single monstrosity. They charge through the streets, promising to burn the world and return it to nothing more than a rusted ball in space.