Breath of Fire: Dragon Quarter

The world is called Deep Earth. The world is a huge underground complex of cities and labyrinths. The world is populated by people who have never seen the sky and the sun in their lives. The world is dark and hostile, and knows no mercy. Technology is well developed in this world, but the society is ruled by a cruel law, dividing all the citizens into classes, depending on the their D-ratio - a form of identifying people and assigning to them a social status at the same time. This is the reality of mankind somewhere in a fantasy universe, where the hero Ryu is thrown into.