Survivor of the doomed Fleed world, Duke Fleed escaped to Earth. On a clandestine spacecraft he was taken in by Dr. Umon, who raised him as his own son and renamed him Daisuke Umon. Years after arriving, the ruthless King Vega and his army threaten Earth"s peace, forcing Duke to face their menace in the face of their relentless assault. Joined by friends Koji and Hikaru, and later his younger sister Maria Grace, he resolves together to defend humanity using the mighty Grendizer.
