Need Help--! D:>

Well, I've been searching for this manga I've read some times ago, and I forgot the title. The story about a boy who comes to a christian school (I think) and one day he witness a girl commit suicide by jumped off the church (or some building I can't remember) but when she dies, a magic circle appears and this hot-human-loving-demon appears and the boy and the demon made a contract.
It involved some fighting inside an alternate space and time, and involving some other hot dudes with their own demons.
I really forgot the title--thanks!