I am 99% sure that all of those hands were just the various horny ghosts crowding in to get a shot of the show and that they looked a lot more innocuous than you'd think.
No one dies or disappears, AND the female character has modestly sized breasts? Quite a departure from Iwasaki Yuuki's norm, and I certainly don't mind it.
Sorta just thrown in at the end. Not expecting much though since they only have so many pages to focus on it if at all because we're all here for the porn.
I'm guessing the apartment next door was one from a previous story. I tried to find out which one by comparing the apartments in the other stories, but to no avail. Maybe someone else can succeed where I have failed.
Well, this was certainly an interesting release. First you think her neighbour is one of those loud types, so he basically had sex with her just to piss them off...But then it turns out...There was no neighbour. And a lotta unknown handprints on the balcony window.
Horror tag certainly fits.