If the culprit is anyone but Syo, Fukawa, Togami, Celestia, Hagakure, Oogami or Asahina, then the answer is coming COMPLETELY out of the blue, and the entire investigation has been nothing but red herrings. Those are the only people who have had anything to do with the changing rooms, Fujisaki, or the whole Identity Card thing.
If the entire investigation has been NOTHING but misdirection, then this game story ends up being kind of stupid, because there's no point in trying to "figure out the mystery" when everything we do gets tossed out the window for something new at the last minute. The culprit isn't Mondo.
oh dear
--
Black Turtle did a pretty good job.