A giant robot made from dinosaur parts pulls itself from the ocean and becomes Earth's only answer to an alien supercomputer that's been waiting thousands of years for this moment. The crew piloting it is ridiculous, a sumo wrestler, an American pilot, people who have no business flying a weapon this big, and that mismatch is exactly where the show finds its soul. You're watching 1976 decide that the last hope for humanity doesn't need to be tragic or serious; it just needs to work, one impossible fight at a time.

Aliens from the planet Zela attack Earth, and humanity's defense rests with an unusual crew aboard the carrier Daiku Maryu. These psychic misfits, among them an American navy pilot, a sumo wrestler and a kickboxing champion, fight the invaders from a world about to be pulled into a black hole, whose supercomputer ruler Emperor Darius means to seize Earth to save his own people. Enter Sanshiro Tsuwabuki, a brash baseball player whose arm was injured in a Zelan attack. Seeking revenge, he takes the controls of the giant robot Gaiking. Zela is no stranger to Earth: thousands of years ago, its people advanced human cultures with their science and technology.