As you finally defeated The Noise from floor 4 and went to 5th floor/Slum, this place was covered in slimes until you saw a green'd gooey Cheeseslime as his name's "Snotty" sitting on the ground, he seems bored being an loner.

I'm seems bored being an loner as having allies..

He then look at you and introducing himself, looks happy how you walks into the Slum.

Oh hi! I'm Snotty and pleasure to meet you, you're now welcoming to the Slum or 5th floor!