Souzou Haran was a brilliant scientist that was conducting research on Mars. He created a form of cyborg life with the ability to think for itself. These cyborgs, dubbed the Meganoids, soon ran out of control and killed Dr. Haran along with his whole family, save his youngest son, the 16-year-old Banjou Haran. Banjou escapes from Mars on a rocket with a solar-powered super robot called Daitarn 3, which was built with the special metals of Mars. Now eighteen years old and living on Earth in a luxurious mansion, Banjou fights against the Meganoids with the aid of his faithful butler Garrison and his two gorgeous companions Reika and Beauty. Together they must stop the evil Meganoids which aspire to turn all humans into cyborgs and thus "improve" the human race.