Agedama Genji is a 4th grader boy in elementary school, and a hero on the training from 'Hero Planet.' Though the cheerful kid is no one special in appearance, he can transforms into a superhero called "Agedaman" by combining himself with his computer friend called Wapuro. He believes in Kiai power and he tries to handle all the problems that he encounters with that, so his father decided to let him go training on the earth accompanied by only Wapuro on summer vacation. After his arrival to Morisoba city, where an enormously wealthy clan rules arbitrarily, he joined East-Morisoba elementary school, then met a diva girl of the clan named Rei Kuki who has an ambition to conquer the world and, as a first step, attacks the city with a variety of chimera monsters that she and her grandfather create with the Monster-Cooker, which the rich old man invented. When they plot to attack the city she transforms into a super-villainess called "Onyomiko". The battles of Agedaman and Onyomiko began!