Seo Jiho used to be a building manager. After being reincarnated in another world, he finds himself in charge of the Gray Spire, a lodging facility facing financial ruin.

The problem? Monsters fleeing a disaster in the west are pouring into the tower.

When the Arjen Kingdom tries to take control of the Gray Spire, Jiho turns the situation around with nothing more than his knowledge of procedures and a few well-placed loopholes. What should have been a forced takeover becomes a lucrative contract to provide lodging and defense for the kingdom.

Then an ancient calamity known as the Abyss appears.

Rather than fight it, Jiho discovers that the Abyss has a taste for refined mana, and offers it a lease.

With an ancient calamity now occupying part of his property, the Gray Spire's reputation skyrockets. Before long, every room is booked, and monsters are lining up for a vacancy.

All Jiho wanted was to run a lodging business.

Unfortunately, every one of his guests is a monster.