在美国西海岸某城市中生活的少年乔伊，过着不怎么丰富但是和平且无聊的日常生活。 在一个雷雨的夜里，乔伊的家里被雷直击了，几天前在垃圾桶里捡到的旧的机器人玩具变得巨大化，有了不可思议的力量。乔伊因为小时候憧憬的英雄在现实里实现而兴奋不已，并且给这个机器人取名为HEROMAN。 但是，这只是一切的开始。乔伊和HEROMAN不得不面对从遥远的宇宙那一边来到的可怕袭击者，并且投身于和他们的战斗之中···

An American kid named Joey lives in Center City, USA & has always wanted to become a hero. Unfortunately, he's just an orphan working part-time to support his grandma and himself. After he watched a commercial of a new robot action figure, Joey believe he'll gain strength if he obtains one. The only robot toy he can get his hands on is a broken one that was abandoned by a rich school bully. Feeling pity for the trashed action figure, Joey took it home to repair it. Little did he know, that once he repairs the toy, it'll make his hero dream become a reality.

在美国西海岸的中心城市，憧憬着HERO的少年Joey一边打工，一边和祖母二人快乐地生活。 某天，Joey捡到了一个破烂机器人玩具并着手修理它，然后为它起名叫“HEROMAN”。而在修理好之后的当天夜晚，一度来自外太空的不明离奇闪电击中了Joey家，机器人玩具被雷光包围，化身成一个拥有电击能力的巨大机器人“HEROMAN”。然后，迷之生命体也开始了对地球的侵略……