Maou ni Natta node, Dungeon Tsukutte Jingai Musume to Honobono suru

A man named Yuki is reborn as a demon lord in a foreign world and given control of a dungeon. He learns that his survival depends on the dungeon's endurance in a dangerous world filled with powerful monsters. He starts recruiting allies and improving defenses. Soon, he gains a legendary dragon, a small slime, and a vampire girl. Despite the threats, life in the dungeon is unexpectedly calm. With a diverse group of companions and more possibly joining, Yuki faces challenges like a risky rescue and an attack from a human kingdom. He balances daily life, his duties as a demon lord, and managing his growing group of monster girls and pets.