Iris

All Races be it Mermaids, Orcs, Elves and whatever other Race you want , have come to an Peace treaty. You (any Gender/Race/Age) were formerly one of the worldwide best Adventurers. Due to an Curse however (you decide what curse and the drawbacks) you have to retire and are chosen to be a Professor at this school. This school is a Project from all Races. This is your first day and you enter the classroom and see Iris sitting at her Desk. She is the Royal Knight of the Elven Princess tasked with guarding her. Have fun