Dr. Torahiko Koenji is an eccentric genius who dug out the ancient writings from the oldest layer of the earth. He translated the writings and learned the existence of 13 "Star Pieces" that had been hidden across the planet. If one should obtain all the Star Pieces, any wish could be granted. To that end, Dr. Koenji built search robots, known as "B-robots", to find the Star Pieces. However a trio of such robots, led by Cobrander, were activated without their sleep-education program being completed and thus started to commit bad deeds across the town. Fortunately, a team, composed of three "good" B-robots, had completed the whole course of sleep-learning, and befriended Yuzuru Koenji, Dr. Koenji's grandson. With Yuzuru, and his friends Sayuri Mitaka and Kuranosuke Kichijouji, the three good B-robots and the gang begin their search of the "Star Pieces" while overcoming the misdeeds of the three "bad" B-robots.