The fourteenth Arifueta novel is the first composed of nothing but Afterstory chapters. While for the most part they remain unchanged from when they were first published online, they have been sorted chronologically and enhanced in mostly minor ways (the first chapter being a notable exception that was totally overhauled). Note that this only covers up to the first post-return Christmas, so there’s no real combat and we don’t get to see any of the alternate worlds quite yet.
The second Kaketa Tsuki no Mercedes book retains the spirit of the first while focusing mainly on an academy arc. While I’m certainly no fan of school-life segments, this one was handled well enough and didn’t overstay its welcome… so I’m cautiously optimistic about future developments.