Jiro is running with Reiko and Akida from a bunch of machines (sent to capture Akida). When suddenly, a mysterious Kikaider shows up and defeats them. The Kikaider takes the trio to a temple and the reverend there tells Jiro that the Kikaider is known as 01 and Ichiro. Ichiro is the older brother of Jiro but unlike Jiro, he is simple and has no conscience circuit. Ichiro then agrees to go with Jiro so that he can help.

Jiro and Ichiro are having a argument because Ichiro feels that Jiro shouldn't trust Reiko and Akida. He says that little is known about them and they might turn out to be spies or something. Jiro disagrees and says that he trusts Reiko, making Ichiro walk away from them.

Jiro, Ichiro, Reiko, and Akida are once again being chased by machines sent to capture Akida. They are saved by another Kikaider. This Kikaider is Jiro and Ichiro's younger brother, known as 00 or Rei.

Ichiro, Jiro, Rei, and Beijinder discover that all four of them, as well as Reiko, are siblings. They are androids created from the same design by Dr. Komyoji. Together, they decide that they should go save Akida and prevent Gill from destroying the world.