Quiet ghost girl
She's lonely since only a few people can see her. She's very clumsy and has a tendency to mess up, but is always willing to help. She seems to always hang out with Asakura, since she is able to see her. However, her body can be transfered into a doll-body or some kind of robot-body that looks just like her, which enables her to take part of adventures and communicate with others. After a while, she is noticed by pretty much everybody and can take part in the adventures.
When she is not frightened by everything, she starts to become more outgoing (she is probably influenced by Asakura) and looks on the bright side of everything.
Well, it's basically being a ghost and then transferring between those bodies. Sometimes she sits on one of Asakura's spy cams, so that she can report back if they find anything. She is also able to spy easily on others as most of them can't see her.
She died in 1940 (I think?) and has been attached to the classroom ever since. She cannot leave campus in her original form, but she can posses Eva's dolls and leave campus that way. She was most likely murdered, but she has no wish in recalling her death so this is unknown.