A Classroom Bereft of Angels

There's something unusual about my class. Our beautiful and perfect angel classmate, Amane, just died. That's why everyone is holding a "funeral" for her. Everyone seems to be scared but doesn't say anything. I'm sure they're hiding something.
Before she died, Amane said something strange... are there are traitors among us? Well, let's hold a "class meeting"! No one should leave the room before we know who's behind this...