The year is 22XX. JAXA, the space science lab, discovers a planet where extraterrestrials live. A space satellite is launched to establish friendly relations with the planet, but the satellite is destroyed in an accident of unknown cause. Contact with the planet fails. Subaru's father was on the satellite… Since the disappearance of his father, Subaru is scared to communicate with people.

The second series follows the events of the second game focusing on the lost continent of Mu. The ancient civilization vanished ages ago, and a few of its remnants still exist as myths and legends called UMAs (Unidentified Mystery Animals similar to FM-ians that also have the ability to fuse with humans).