Summer 1976

A gigantic prehistoric creature called Dragonsaurus rises from the sea and begins consuming enormous quantities of oil, growing into a threat powerful enough to devastate Tokyo. Conventional attacks barely slow it, forcing Earth's greatest super robots to face the monster together.Grendizer, Great Mazinger, and Getter Robo G combine their strength against an enemy that can regenerate its severed limbs and withstand devastating weapons. The battle grows even more urgent when the overeager Boss Borot is swallowed by Dragonsaurus, leaving the heroes to rescue their ally while stopping the creature before it reaches the city.