Alien forces seize Great Mazinger, which stands at the entrance of a museum next to Mazinger Z as symbols of peace. Grendizer engages the invaders in battle, ultimately restoring Great Mazinger to its rightful place.
The Vegan Empire dispatches a new general to oversee Earth"s occupation; he quickly captures Koji Kabuto, interrogates him for information about Great Mazinger, and commandeers the robot from its museum display.
Now Duke Fleed aboard Grendizer must stop humanity"s former defender from becoming the very destroyer it once protected. He must act before it wreaks havoc across the planet.
