Piron no Himitsu
ピロンの秘密
Two brothers, Tetsuo and Akio, encounter a boy named Piron while camping in the mountains. Piron is the prince of the star Castor in the Gemini constellation, whose father was overthrown by the minister Valles. To escape Valles' assassins, Piron fled to Earth with Mira, a robot. The brothers join forces with Mira to protect Piron from those sent to eliminate him.