In a desperate attempt to save themselves, mankind created a superhuman race of machines called Neo-roids; however, the robots have taken total control over the Earth, enslaving man to the point of near extinction!

All is not lost however. A beacon of light shines in an age of darkness, for a man-machine with extraordinary powers gives new hope to the masses. The time has come to take back contro. The time has come for Casshan, Robot Hunter.