Souzou Haran was a brilliant scientist conducting research on Mars. He created a form of cyborg life capable of independent thought. These cyborgs, dubbed the Meganoids, soon got out of control and killed Dr. Haran along with his entire family, except for his youngest son, 16-year-old Banjou Haran. Banjou escaped from Mars aboard a rocket with Daitarn 3, a solar-powered super robot constructed from special Martian metals. Now eighteen years old and residing in a luxurious mansion on Earth, Banjou battles the Meganoids with the help of his loyal butler Garrison and his two beautiful companions, Reika and Beauty. Together, they must stop the evil Meganoids, who aim to turn all humans into cyborgs to thereby "improve" the human race.