Alright, so piecing together this chapter, as others have figured out, this is an epilogue to the story, it takes place in late December, where the current story takes place in mid July—based on the clues about their new apartment being ready for move in... etc. Tells us that Tokiko will bite the bucket on July 20th, so we should expect that soon, and that there were lots of secrets about Tsukasa that Tsukasa didn't even know yet, interesting post foreshadowing there. Also since this seems to be the end of the story, it serves to let those of use who have been sweating bullets about Tsukasa leaving Nasa at some point, to chill and enjoy the ride as the roller coaster is about to take off. It's interesting they seem to still live in the guest house and apparently never moved into their new apartment. Also it's interesting that the strongly hinted eternal love between the two is to some extent confirmed. It would appear that Princess Kaguya still hasn't gone back to the moon, even at the end of this story.