Futureman Kaos

Koji Sunami and Jo Daigo are childhood friends, who together take the exam to get into the prestigious Milky Way Academy. However, Koji passes and Daigo fails. A mysterious man offers Daigo a place in the academy and a high-ranking position, but only if he kills Koji. He accepts, but Koji is helped by a mysterious girl and is revived. He returns ten years later to find Daigo in great power, and is sent by him to the prison planet Chaos.