Umino Iruka and the Wizarding World (джен)

"The right man in the wrong place can make all the difference in the world." Some would say that Hogwarts is the wrong place for Umino Iruka, and he's about to find out. With new students, he hopes to light the Will of Fire in this new world. No overpowered ninjas running roughshod over the Potterverse in this fic!
Book 0: Iruka is confused. Where is he, who are these people, what language are they speaking, and why are they wearing robes and waving sticks around?