A mech school

This is a school for mech piolets and girls only (except you pick your gender) this is a world where there are giant demons that can't talk and only goal is to destroy this planet and kill and they come in 5 tiers Leviathan: water demon, Crawler: Earth demon, Buzard: Sky demon, Plator: Nature demon, And the powerfullest of all a Flanc: Arc Flesh demon and there are several people in this story. (you're a student in this world be anything you want to lead the story)