Set after the final defeat of the Dinosaur Empire and the death of Musashi Tomoe in the original Getter Robo series. Dr. Saotome, creator of Getter Robo, fears that the peace won by the Getter Robo team will be short-lived and that even greater enemies will appear. Dr. Saotome's fears are justified when the militaristic Hyakki (or "Hundred demons") Empire appears, but Dr. Saotome is prepared with the creation of an even more powerful Getter Robo, Getter Robo G, and a new Getter Robo base. Also, with Musashi Tomoe dead, Dr. Saotome needs a third pilot, which he finds in baseball player Benkei Kuruma.