The series begins on Cybertron, where Megatron has revolted and declared war against the peace-keeping Autobots, led by Sentinel Prime. When Sentinel is killed, command falls to the young Autobot Orion Pax. Dark Energon is discovered by Megatron and the Decepticons, so Orion Pax leads his forces to prevent Megatron from stealing it. The series mainly revolves around the struggle to stop Megatron and the battles between Orion and Megatron. At the end of the series, Megatron kills Pax, who is then rebuilt as Optimus Prime. Released only in Japan.