The Hitting Zone - Chapter 10: The Arcade

One day, I woke up only find out that I’d become a Demon Lord, an individual responsible for protecting a dungeon. The world I’d been spirited away to was one filled with violence. Gigantic monsters wandered through it and competed with each other each and every day for the right to survive. I had no choice but to strengthen my dungeon’s defenses in hopes of living another day—or at least that was what I’d thought. For some odd reason, I instead ended up spending my days in relaxation and bliss.

Yo, Hi! I’m Frank, I made a deal with a demon to pay me some money for receiving a guest for a few days every week.
I had no idea about what I have done.
On May 1st, Conan ‘the God of Death’ came to my house. I was forced to let him in and we get involved in a criminal case.
On May 8th, Bruce Wayne ‘Batman’ came to me. I was forced to follow him to fight crime.
On May 16th, Hannibal Lecter, The Silence of the Lambs, came to my home. I can only say that I really can’t stand my guests.

- Description from Novelupdates

Due to a mistake on his student’s part, a super Martial Artist had received a wrong class in an online game and had become a mage. He who was used to curbing violence with violence and using strength to subdue strength could only make the best out of his mistake. Taking on a new lease in life, he became a violent close combat mage. When strength and magic came perfectly together, a new gaming path had been opened by him!

The empire has turned into the land of the undead due to a spell gone wrong. God summoned heroes from countless worlds to purify the empire and plant new hope. Lee Shin Woo, an ordinary earthling, was also summoned. As an undead, that is.