High school student Koji Kabuto goes with his childhood friend Sayaka Yumi to visit her father, Nobel Prize winner Gennosuke Yumi at the sight of mysterious Greek-like ruins. Suddenly an Earthquake occurs and Koji falls into the ruins. Within the ruins, Koji discovers the body of the Olympus warrior Zeus. With the revelation of Zeus, came the invasion of the Mechanical Beasts led by the incarnation of Hades, Dr. Hell. Using the last of his strength Zeus strikes a blow at the invading Mechanical Beast. With Zeus's body salvaged, it was remade into a robot for Koji to pilot against Hell and his invading Mechanical Beasts.