Dr. Yamanoue, the Secretary of the Science Ministry, assembles the Android robot Jet Mars on an artificial island in 2015. He considers Mars to be his own son, but their differing backgrounds and personalities create tension. Dr. Kawashimo, a friend and rival of Yamanoue, visits the island with his young daughter Miri to repair Mars' defective electric brain. Miri turns out to be a highly capable individual, and her bond with Mars helps him learn valuable lessons about humanity.