Not the first I've seen. And usually, when the isekaied MC is the landlord, it means good things for the people living there (until someone decides it's too good and want it, so there's war and whatnot).
Just saying, but if Note can pull towels and the like from a skill called hidden weapon, it's because the system that governs over the skills in this world recognizes that he can use towels and the like as weapons.
They probably just topped a dungeon flood as if strolling in a park, or more like playing in a fair. Shadow boss is probably going to come to the dungeon looking to start a stampede and be like "Where are all the mobs?".
Talking about hats, hats off to the spy girl here. She's so skilled she was hanging from the 4th wall there for a moment. It's not some feat that anyone can do.