Humanity was once in danger of its downfall at the hands of the Underground Empire, which was led by the evil scientist Dr. Hell. Koji Kabuto piloted the super robot Mazinger Z, and with help from his friends at the Photon Power Laboratory, he thwarted Dr. Hell's evil ambitions and returned peace to the world. It's been ten years since then... New encounters, new threats, and with humanity's fate in their hands, Koji and Mazinger Z face a choice between good and evil -- once again entrusted with the future of mankind!