This seems way too dues ex machinates to me. Who the hell keeps 3 bottles in their pack. I can imagine 1 with a 1-2 replacement filters but 3 bottles, the hell. Knife would have been noticed before no? With him being "bullied" I would have taken shot from his bag. Also there wouldn't be any...
This is what I would expect from most people that have been isekai'd while depressed. Just cause I'm in another world doesn't mean I think I have a better self worth.