Due to an accident, Zhan En arrived at another world and was reborn as the son of the Devil King. In this far-reaching Underdark, he became the master of the Dungeon and successor of the Devil King. However the dangers from the darkness haven't stopped there, as there is the devil race who's thristing afer the position of the Devil King, the monsters hidden in the depths of underground, the adventurers scurrying about for treasures and legends, and the knights from the surface that are fighting for justice. Under the ancient oath and banner, Zhan En holding a scepter in his hand, will bring unprecedented changes to the world from the dark depths of the underground. Klein, a continent that has experienced countless storms, is about to turn a new page once again.