A Misanthrope Teaches a Class for Demi-Humans, Vol. 1: Mr. Hitoma, Won't You Teach Us about Humans...? (novel)

I'm Rei Hitoma, a self-professed misanthrope thanks to some past trauma. Just when I thought my new teaching job in the mountains would provide a chill, rejuvenating environment, it turns out that this school is actually for demi-humans who want to become full-fledged human beings! There's a mermaid, a werewolf, a rabbit, and a bird...all of whom are now my charges. It's my duty to teach them about humankind-and maybe in the process, I'll learn a few things myself.

This isn't an alternate world or a case of reincarnation. It's just the story of a teacher at a somewhat peculiar school, and his students who are striving to become human.