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!

Seeing Heroman's power before his own eyes, Joey wasn't able to hide his happiness or bewilderment. He worries about what he should do with this power and what Heroman really is. Meanwhile, the mysterious life forms called "The Skrugg" have begun their Earth invasion. When Joey hears of it, he runs to tell Prof. Denton who was broadcasting to them of the imminent danger. However, the Skrugg appear there with weapons in hand! And Lina encounters them as well!?