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When a meteor crashes to Earth, it briefly changes the climate and dinosaurs once again roam the planet. It's up to a newly formed expedition team to relocate the dinosaurs to a safe environment.
The story takes place 1,000,000 years since the Dino Knightshad last defeated the Dragozaurs. The Dragozaurs have returned, a boy named Kaito has reawakened them. The battle between the Dino Knights and the Dragozaurs begins once again as the Dino Knights prevent the Dragozaurs from stealing Earth's life force.
Many years ago, Duke Fleed fled to Earth with the mighty Grandizer robot to prevent it from falling into the hands of the Vegan Empire. Hiding the robot and taking on an Earthian persona, he vowed never to pilot Grandizer again. Fast forward to the present, and a group of UFOs led by his childhood sweetheart have tracked down Duke Fleed once more. Demanding Fleed turn himself over, they give him a choice: return the Grandizer or watch Earth be destroyed! Will Duke Fleed stand by and watch his adopted home be obliterated, or will he break his vow, pilot Grandizer, and face off against the combined Vegan UFO Fleet?
Mars is discovered on a forming volcano island, Heisei; a man with no memory. In reality, Mars is from outer space, and is supposed to gather information to decide whether Earth should be destroyed or not. Along with the giant robot Gaia, and his mysterious images of a woman urging him not to destroy the world, Mars decides to fight for Earth rather than destroy it, even if it means fighting his own kind. But if Mars is killed, Gaia will explode, destroying Earth along with it.