Remember Everyone this Naive thinking of "Do not kill humans." When transported to another world is "PEAK JAPANESE MENTALITY" and is BS in a world where you're outnumbered 10 to 1 (excluding the soon-to-be brainwashed students).
Only the "RIP and TEAR your enemies until it's done" mentality is accepted.
I find it funny how all of you harp on about how he's naive for not wanting to kill humans but if someone put a gun to your head and told you to kill someone you wouldn't be able to do it. There's a reason soldiers need to undergo training. Normal mentally sound people can't just kill other people.