Board Thread:General Discussion/@comment-26199823-20150111173458/@comment-101.189.88.127-20150112073756

Ruri is shown to be wearing Academia's uniform and found within their facilities. Like you said, she could have betrayed her group or:

The Professor could have brianwashed her

They could have removed or rewritten her memories

Or Ruri is pretending to be on their side or something along those lines (Like an agent)