Eternal Dungeon: My Master is a Total Monster... Isn't He?

Klay was a nobody. A sleep-deprived gamer, ignored by society, invisible to classmates, and addicted to a dungeon grinding game he was terrible at. But then one night he suddenly woke up in a different world, one eerily similar to the very game he was playing. Except this time, he was not just a player. He was chosen as a contender for the ruler of the dungeon.