Montecristo was a devil who, due to the betrayal of his subordinates, suffered defeat at the hand of humans.
At the last moment, he was granted a final miracle.
He succeeded in returning to the past before all of his misfortunes began.

However, his body had shrunk in the process, and he was now the size of a small child...

A demon, defeated by the world and abandoned by his subordinates...
Knowing what the future had in store for him, he made up his mind.

The only thing I can rely on... is the dungeon!
And who the hell betrayed me anyway?!

[...]

Based on the popular Korean internet novel called "Dungeon Lord"

[From Steam]