Yuu's breakdown was something I didn't know I needed to see. I thought we were seeing a lot of visual metaphors for angst when, no, she's truly having a mental crisis and on the verge of hallucinations.
If Yuu really is an alien, I'm expecting an alien to arrive. As another human, probably a local, with no evidence of anything scifi going on other than an unverifiable psychic ability. If Yuu isn't an alien, just a psychic, she must have been through a some really painful ordeals to reach this state, and that's coming out realistically.