Center City, West Coast, USA. Joey loves heroes, and lives together in the city with his grandmother. While working a part-time job to support himself, he enjoys his life surrounded by Psy, his sarcastic lone-wolf friend, and Lina, a bright, cheerful girl from a well-to-do family. One day, Joey picks up a toy that was thrown away, repairs it, and names it "Heroman." But just then, a bolt of lightning strikes the toy! To Joey's surprise, a giant-sized "Heroman" is born before his eyes!

Faced with the extinction of the human race, the President is coming closer to deciding to use nuclear weapons. But before him appears the mad scientist, " Dr. Minami." He claims to be able to stop the sphere without using a nuclear attack. Back in Center City, Joey and the others are infiltrating the Skrugg's base, and in order to cause a diversion they split into two groups. The newly re-brainwashed Will and Nick appear before them. Joey has a plan to undo the brainwashing, but...