Dr. Saotome, the mind behind Getter Robo, worries that the harmony secured by his team may soon crumble and that a far more formidable foe could rise. His concerns prove valid when the militaristic Hyakki, or 'Hundred Demons,' Empire emerges; yet he counters with the development of an even mightier machine, Getter Robo G, and a fresh base. With Musashi Tomoe gone, Saotome must recruit a third pilot, which he discovers in the baseball athlete Benkei Kuruma to face for the new coming ahead threat.