For those interested, Yuuko is a ghost, in her own canon, she haunted teh site of her death for over 60 years, wandering the school that was built over it. She's a kind, upbeat, fun, but mysterious presence that seems ot be tied to many local ghost stories. Only certain people can see her, thought those that are spiritually aware would be able to see her as well, like say Lala, or Yuri. THe idea we've come up with is that Yuuko is imprinted on an actual ghost and as such, wanders the mansion, sometimes hanging out with the group as if she were really there. As far as Yuuko knows, no one can see her, or has seen her since she suddenly found herself wandering the mansion halls a couple weeks into hte time skip (so a couple weeks ago). She has no memory of her own world, and only knows that she's a ghost, haunting this mansion because, in her words, She was drawn to it. But the lack of memories doesn't seem to keep her from being in an almost perpetual good mood, and she seems to have a bright outlook on the prospect of spending her time watching all of us.
However, she doesnt come alone... The rarer sight is a dark presence. The other, seperate half of Yuuko. Press Yuuko too hard, or back her into a corner, and it may draw out the Other Yuuko...