The game is set in the dystopian, post-apocalyptic future setting of the planet Terra, where people exhibit kemonomimi features – characteristics of animals or mythological races. Natural disasters leave behind a valuable mineral, originium, which infects people with a progressive disease, oripathy, but also allows them to also use "Arts" (magic). Because oripathy is highly infectious and invariably mortal, the infected are shunned and persecuted. In response, some of them form the Reunion.