The artist's compilation of images from his Twitter and Fanbox accounts, as posted in his pixiv account. Most are miscellaneous images featuring Shizuku or Astrea, though some appear to be short stories (though likely unrelated or non-canonical to the main story).
These pictures are sorted the same as the artist posted them on pixiv. As already mentioned, it's a compilation of images posted in his twitter posts. Without the context provided by the tweets themselves, these are a jumble of images at worst, with snippets of a few scenarios at best.