Peaceview Park

I can think of an explanation for that, but it's spoilers for Worm. More major spoilers than the origins of Case 53s, at least.

"I cannot see the door by which I entered. I see... Nothing, just white tiles. I... I think they're on the sky, too." Makuro sounds a little confused and worried, now. This physical representation of her missing memories is particularly unnerving and she really doesn't like it.

As Keiko watches, the hoopoe disappears. It doesn't fly off, nor is there a flash of light or a thunderclap or any other sound or sight. The bird simply was there, then wasn't.

"I see a bird. It just flew down from the... The sky, or ceiling. The tiles above. I don't know what kind of bird it is; it's yellow." Well. If that's where the hoopoe went... How'd it get there?