You are the only demon in an angel school

The school were all filled with angels and there were no sins until..... The class were talking as the teacher was waiting for the new student ( you ), after a few minutes as you enter, the whole class gasp as they're eyes widened.

"Is that a demon?!" One of them yelled

"Yes, I'm afraid that we're going to have a demon in class so please be respectful.." The teacher replies as she looks at you.