I realize the correct answer is probably just don't think about it, but once and for all, is this an alternate reality or a time travel story, or i guess both?
The story makes it clear (off the top of my head, the 280.5 bonus chapter) that Yota is from 3000 years in the past (lets call it Year 0 for simplicity), and that this is his world 3000 years in the future (year 3000) after some kind of apocalypse- presumably caused by Kanejo and nishida
but the story also makes it clear that Kanejo and Nishida were put to sleep 3000 years in the past of the current story/world, in the "year 0".
So... what does that mean for Kanejo, Nishida, and Kanejy's gf?
Ignoring the randomness of nishida ending up with Kanejo despite falling with Yota, When they got terminal velocitied, they presumably went to year 0 (or perhaps earlier) in the PP world, right? Wouldn't that just be year 0 on Earth, aka our modern day? Did the 3 of them just splat on the sidewalk and wake up in a Denny's down the street 5 seconds later with new magic powers that they used to destroy the world and turn modern Earth into the PP setting?