UFO Robot Grendizer vs. Great Mazinger

Theatrical feature. When the Vegan empire dispatches a new general to oversee the takeover of Earth, he quickly manages to capture Koji Kabuto and, learning of Great Mazinger through interrogation, quickly comandeers it from a museum where it was kept as a symbol of peace. It is now up to Duke Fleed and Grendizer to stop humanity's former defender from becoming its destroyer.