During a fateful encounter at sea, Tsuwabaki Daiya witnesses a mysterious black fire that swallows his father and crew, only to be rescued by a colossal mecha dragon. Fast forward five years, Daiya navigates the challenges of junior high when a monstrous threat resurfaces, leading him to reunite with the mecha dragon, 'Daiku Maryu.' As the dragon transforms into the formidable super robot, Gaiking, Daiya pilots it to vanquish the menacing foe. Unveiling a sinister world domination scheme, Daiya embarks on a journey to the parallel realm of Darius to thwart the impending threat.