Imo I think his decision of hiding and running is a good choice as how are you gonna kill or defeat a group of thugs who are completely unhinged and won't stop at anything(even kill their own teacher and classmates) and people willing to do their bidding inorder to survive with just 9 people. You are completely and utterly out numbered.
Plus I think the one thing most people are forgetting is that the MC is just a high schooler with a hobby of being a survivalist not an ex millitary veteran. Even if it's just killing the leaders those d**k for brains won't come alone to let him kill them, even with traps, it will be hard to actually kill literal humans with basic education and understanding of his/her surrounding with just survival knowledge. And the a-hole has a f***ing GUN 🔫. He can almost severely injure them and from them I mean the meat shields as those lustful cowards aren't gonna charge in by them selves
For the mc it shouldn't be hard. Fundamentally, these are all city kids, and he has survival skills that would place him among the best in the world, including hunting and trapping, plus the ojou-sama girl's attendant is a strong fighter who seems to have undergone the kind of training that would prepare someone to kill. If the two of them made it their primary goal, I don't think they would have much difficulty catching the leaders of the other camp with punji or log traps.
Smoke would be a very effective weapon to use on that group because they are all taking shelter in caves, and this type of wet, tropical island would be basically impossible to accidentally start a forest fire on.
