Daihachirō Yamada plots to seize the valuable gemstone embedded in the forehead of Konpei Island's last dragon, distinguished by his Hitler-style mustache. He commands an arsenal of advanced technology, deploying destructive mecha units that include a specialized mechanical sumo wrestler. To bolster his forces, he contracts the skilled mercenary Michael Commando to battle the island's guardians. Yamada's strategy combines this mechanical might with hired military expertise to crush resistance and secure the dragon jewel. He personally orchestrates these attacks, overseeing the operation to acquire the precious stone.