Humanity is under attack by the Oni - fierce demons of unknown origin - that can only be defeated by Dr. Saotome's Getter Ray-powered robots. However, these robots are only a stopgap, buying time for the next generation of Getter-powered robot: Getter Robo. Able to change shape into three combinations to suit the current task, and vastly more powerful than its predecessors, Getter Robo requires three pilots to fully utilize it. Dr. Saotome selects three interesting individuals for the task: Ryoma Nagare, a headstrong martial artist; Hayato Jin, a power hungry terrorist; and Benkei Musashibou, a bear of a man who has turned to the way of Buddha. Together, these oddly-matched teammates must find out where the Oni come from and stop the threat that they pose.