Former Title: The Weakest of the Four Heavenly Kings Creates the Strongest Dungeon ~Those Who Laughed at My Incompetence, Harmed My Subordinates, and Banished Me Were Purged for Failing to Manage the Dungeon, and Asked Me to Return as the Demon Lord, But Creating a New Dungeon is Fun and I Don't Care~

[Book Edition Vol. 1 scheduled to be released by Earth Star Novel on February 16, 2022!]

「It's presumptuous for a mere chore boy like you to claim the title of one of the Demon Lord's Four Heavenly Kings, just like us!」

Kaitoshade, a young demon who inherited the ability of 『Dungeon Create』 from the previous Demon Lord.

However, because he almost single-handedly managed everything from the maintenance of the "Demon Lord's Castle," the strongest dungeon already completed by the previous Demon Lord, to all other chores, other demons mocked him as a mere chore boy capable of nothing else.

One day, the Demon Lord took a liking to a powerful demon he had befriended during a subjugation mission. To appoint this new demon as one of the Four Heavenly Kings, he branded Kaitoshade useless and banished him.

「Kaitoshade, I bestowed upon you the title of one of the Four Heavenly Kings out of respect for the previous Demon Lord, but someone like you, capable of nothing but chores, is useless!」

Furthermore, he cast aside Kaitoshade's subordinate who tried to protect him.

Even Kaitoshade, usually calm, finally lost his patience with that attitude.

「I'll leave the 『Core Room』 for managing this Demon Lord's Castle fully open for you, so please, manage it yourself, Demon Lord.」

Kaitoshade, who had escaped from the Demon Lord's Castle, took his subordinate—a beautiful vampire girl who had miraculously survived—and decided to create his own new 『Dungeon』.

However, the Demon Lord and his followers who had banished Kaitoshade didn't know.

They didn't know that Kaitoshade, who had mastered dungeon maintenance in a harsh environment, had actually become the world's greatest 『Dungeon Creator』.

And because they drove Kaitoshade out, the Demon Lord's Castle gradually began to collapse.

Meanwhile, Kaitoshade built a new labyrinthine city in the frontier, and he began to be called the new Demon Lord.