Dungeon Builder: The Demon King's Labyrinth is a Modern City! (Manga) Vol. 12

I CAN DO THIS ALL DAY... Balam just won't stay down. After his "death," Balam's darkness has spread far and wide, turning everyone it touches mad.

Procel's dream of a utopia for both humans and demons seems unreachable, especially since the Creator is about to destroy the world to stamp out the darkness once and for all. In a desperate move, Procel asks the Creator for just one day to turn the tide. The Demon Lord of Dragons Astaroth joins Procel for the defense, but with Balam gaining the powers of the Demon Lord of Fire, will a single day be enough for Procel and friends to save the world from apocalyptic destruction? The final volume!