Toha case , the world

a story about a guy reincarnated into an Ou Ma( Ou = king Ma=Demon) which is the highest kind of monster, born at the Dragon's hot furnace labyrinth (too lazy to make a proper name for it) gaining power as he was capturing the dungeon while being a monster he met a dying knight which became his godparent and gave him a name which is "Revuu" and accepted the dyings knight's request to take his pendant to his daughter. then when he reached the lowest level, he fought against a black dragon. then after defeating it the black dragon taught him how to change his form into a human. then when he changed he, no , she turned into a little girl with gray hair and eyes and had an inhumane beauty which rivaled none. He had 2 goals, No 1 Goal To defeat God, No 2 Goal to become the strongest being.