Gensou no Idea: Oratorio Phantasm Historia

Seven years ago during the great disaster Naglfar Night, a shift in the Earth’s crust caused the land to be inundated by the sea, washing away the soil and drastically altering the world. A great tear in the crust known as the ‘parallel out’ emitted noxious gases which hardened the skin of humans, causing them to crumble into dust. This spelled the end of tens of thousands of people.