AD 2045 is the tenth year since the "Red Fog Natural Disaster" broke out. Ten years ago, the world was suddenly shrouded in corrosive red mist, and 70% of the land was submerged. The remaining land mutated into "rust soil" containing toxins. Ordinary plants could not survive. Animals were affected by the red mist and evolved into aggressive "abnormal beasts". However, some docile animals can evolve into "evolved beasts" that can coexist with humans under certain circumstances. Human survivors gathered in the "Fortress City" and relied on synthetic food to survive. The outside of the city was called the "Fog Wasteland", where resources were scarce and dangers abounded.
