Could just be a weird/cutesy way of saying "to find out what happens to these two in the future, refer to the story you just read!" Since that last page specifically was a flashback to them in highschool. Maybe it was an omake released separately from the main story, and got collected together in the anthology? It's just a guess, since I don't actually know how these were released.
The moon thing was a little weird, though. Then again, so were the boyfriend-glasses, so maybe Canno just thought "What's a good excuse for this thing existing? Magic? Sci-fi? Sci-fi works. It's AR or whatever. Do I need to add more future junk? I don't really wanna do much worldbuilding for this one-off thing, so... Fuck it, just say they're on the moon. Good enough!"