The Gaira aliens, hidden in the Arctic, plot to conquer Earth. Captured and forced to work for them, Dr. Yan engineers the ultimate weapon: a transformable aerial robot called Gloizer X. The robot is entrusted to his daughter Rita, but it breaks free from the Gaira and lands in Japan. There, pilot Jo Kaisaka encounters a wounded Rita, takes control of Gloizer X, and the two join forces to fight the Gaira invasion.