Ember Martial Age

In 2175 AD, the earth was divided by an eternal energy barrier-the above world and the underground world have since become two species. The truth of the "Great Subsidence" is buried deep in the official archives. People only know that: above the ground, sunshine, green fields and clean air support two billion "new era citizens"; below the ground, 3,000 man-made dome cities are crowded with 6 billion "remnants of the old generation".