A flock of the creatures attacked the planet Terra - a planet in our solar system which humanity had not yet discovered - but were repelled continuously by the Terran's guardian monster Guiron. When two young boys accidentally end up on Terra, they watch as Guiron battles a Space Gyaos. Space Gyaos fired a sonic beam from its mouth - only for it to deflect off Guiron's blade and slice off Space Gyaos' right foot. Initially flying off, Space Gyaos returned in the hope of destroying Guiron in an aerial attack.