"Rhea Gall Force" takes place in the aftermath of the "Stardust War", but before the events of "Earth Chapter". In the 21st century the Earthen discovery of derelict alien technology on the Moon—which are in fact the remnants of the events in "Eternal Story"—ignited an arms race as the "Western" and "Eastern" blocs rushed to deploy the technology as weapons, including a form of artificial life based on the Paranoids, the MME. This artificial life turned on humanity, starting a war of extermination against their creators.