Yuki finds himself reborn in another world as a demon lord, and he’s been put in charge of a dungeon to boot! Knowing his fate hinges on the dungeon’s survival, he begins bolstering his defenses and gathering allies—a legendary dragon, an adorable pet slime, and a vampire girl. Yet despite all his precautions, life as a demon lord in a dungeon constantly under threat is...surprisingly mellow? Of course, with such a colorful cast of characters in his makeshift monster-girl family, Yuki’s bound to wind up in some trouble. And trouble is exactly what he gets when a heroine arrives on their doorstep to take down the demon lord yet ends up bursting into tears instead!