While sailing with his father, Daiya witnessed an unusual black fire. This led to a terrifying incident where his father and crewmates were taken by a monster from the flames. However, he was saved by a colossal mecha dragon that appeared out of nowhere. After five years, Daiya was now a junior high student and reunited with the mecha dragon, known as "Daiku Maryu," to confront a new nefarious monster alongside a super robot, Gaiking. This battle unveiled a malevolent force seeking to dominate the world, which prompted Daiya to embark on a journey to Darius to thwart their plans.