In spring 2133, an unprecedented cold wave swept the globe, bringing relentless [Cryosnow] and [Snowglow]. Humans exposed to [Snowglow] gradually lost memory and consciousness, fell into a deep sleep, and eventually perished. To sustain society, the United Government established shelters and an automated supply network to keep them operational.

In 2150, supercomputers predicted a new surge in Cryosnow storms, causing mass panic and plunging society into chaos. Internal conflicts destroyed several shelters. The United Government confirmed that current technology couldn't withstand the disaster and initiated the [Cryosleep Initiative]. As part of this initiative, the construction and experimentation of [Etheria] began on an artificial island near the equator in the Pacific Ocean...

In November 2174, the United Government officially launched Etheria. Qualified individuals entered hibernation zones beneath node cities to undergo hibernation and Etherization. Their minds, consciousness, and memories were converted into Etheron Data, stored in the Etheron Database, and linked to Etheria. Simultaneously, the United Government formed a defense guard unit, using intelligent machinery to protect node cities and Etheron Hubs. In this era, humanity ventured into two worlds: one chose reality, the other Etheria.

Today, Etheria's most dazzling central city is Eltrise. Embracing Etheria's prosperity, humans quickly immersed themselves. Here, they rediscovered their lives, dreams, and hopes. They entertain, work, socialize, and fall in love. Every new beginning unfolds here, creating a mesmerizing illusion that makes them forget harsh reality and the sorrow of loss. However, this prosperity and peace did not last. External threats, internal conflicts, and tensions between humans and Animuses quietly brewed...