Searching a manhwa

So, there's this manhwa about a school full of monsters,werewolf, zombies, doggies etc. And the director contracts a human to teach all of them. But, nobody knows the teacher is human, because otherwise they would eat him. The thing is, the teacher himself has something mysterious, and that's the real reason the director accepts him in the first place. The genre of the story is horror,comedy and drama I think?
The manhwa is in full color, and it seems to me that it was on format webtoon.
Sadly, I don't remember the name. Last time I see it was in mangafox.
Someone can help me find it?
Sorry my bad english people.