...44 EPISODIOS

Planet Zela, in the sigma atmosphere of the Swan galaxy, was culturally and scientifically very advanced. One day, though, the planet is threatened by an approaching black hole. The inhabitants of the planet build a sentient giant robot, Black Darius, who is supposed to lead them to safety. Black Darius builds, in turn, four more robots, "The Great Four," its aides-de-camp. After decreeing every single Zelan's transformation into cyborg and their retreat in the planet's underground, Black Darius makes preparations to conquer Earth. Our planet, though, is not unprepared to face this threat: Dr. Daimoni secretly built the Space Dragon, a gargantuan fortress shaped like the mythic beast. Inside the Space Dragon there is the super robot Gaiking. After recruiting, almost forcibly, the young baseball champion, Sanshiro Suwabaki, the Space Dragon's crew is ready to start a cruel war against Black Darius and the Great Four. As it is customary in every robot-themed series, Gaiking enjoys an improvement of its weapons, both to have a change and to draw more attention from the public. After several attempts to subdue Earth, Black Darius comes up with a plan to destroy the planet once and for all. It manages to entrap both the Space Dragon and Gaiking on Mars while it, along with its Great Four, arrives on Earth. The Space Dragon and the super robot, Gaiking, manages to get back to Earth in the nick of time. The space fortress destroys the Great Four as Gaiking destroys Black Darius' central computer. At the end, our heroes see a sort of falling star up in the sky… it is a starship built by the few Zelans who had not been enslaved by Black Darius. 

Entry from Anime

Sanshiro Tsuwabauki, a young, extremely gifted baseball player, is recruited to pilot a giant robot, Gaiking. Before turning into the powerful automaton, it looks like the head of a huge space dragon hosting a miscellaneous crew, one of whom is Midori Fujiyama, an alien girl adopted by the base's professor. The nemesis is made up by the people from Zela, once peaceful, forced to retire in the underground due to a natural catastrophe, and to entrust their lives completely to machines. Their society, as time went by, took on more and more militaristic features. […] The series was directed by Tomoyoshi Katsumada of the Japanese TV networks. Character design is by Akio Sugino. The original idea is Go Nagai and Dynamic Productions', not appearing in the credits, though; for this reason Go Nagai sued the company and stopped every collaboration work with Toei Doga.