One day, a package is unexpectedly delivered to a schoolboy, Kohei Kuji. As he opens the box, he finds five action figures. Surprisingly, the action figures begin to move around and start talking to him. They introduce themselves as “Microman,” who have come from the Micro-Earth located at far end of the universe. Their names are Arthur, Izamu, Walt, Edison, and Ordean. The Microman explain their mission, telling Kohei that the earth is now threatened by an evil power known as Acroyer, who is now conspiring to conquer the universe. The Microman have been sent to save the earth. But they need Kohei's help!