Shachiku Tamer, I'm Unconsciously Unmatched Thanks to My Cute Slime.

In the modern world, "otherworldly dungeons" suddenly appear. Dungeon exploration streams by glamorous streamers have become incredibly popular, and dungeons are now the world's biggest form of entertainment. Meanwhile, Yamaoka Eita lives a life of corporate slavery, completely detached from this world. His only pleasure is playing with his pet, a slime monster from the dungeon. However, the floor Eita and the slime were playing on is an uncharted level, barely accessible even to top streamers—!?

(Source: Ultra Jump, translated)