Reincarnated without memories, given a second chance as a chimera with a limited lifespan. Leon struggles through his strange new life. He attempts to improve his dungeon and evolve himself to live longer and become the strongest Dungeon Master—no. The Dungeon Overlord.

Helped by his Dungeon System: the mysterious Ifrit, Zafira, a Level 100 Succubus Queen, and his band of trustee goblins. Leon aims to overcome his limits, survive and reach the pinnacle of the world. Whether through trade, domination, or tricking the hero's beautiful party members into becoming his private mercenaries.

Leon will face the weakest and strongest beings in the magical world of Umbra and surpass all!