I'm a librarian who loves anime, manga, and reading a wide variety of genres.
First story: A black Nyanko-lookalike steals the Book of Friends. Second story: Natsume meets a firefly yokai in love with a human who used to be able to see her. Third story: Natsume meets other exorcists chasing after a yokai-eating yokai. Again, he learns that not everyone feels as much empathy for yokai as he does. Fourth story: Natsume raises an egg, and then the little yokai that hatches from it, protecting it from a yokai that wants to capture it because it's considered to be a delicacy.
Yet another volume with lovely, bittersweet stories. The theme for this one seems to be lack of permanence. Humans die much sooner than yokai – Nyanko-sensei reminds us that he outlived Reiko and will likely outlive Natsume. Also, this is the first time it occurs to Natsume that his ability to see yokai might not stick around forever, and that this thought doesn't make him happy, even though his abilities caused him so much pain over the years.
The latter half of the volume wasn't quite as good. The bit with the exorcists opened up the world more and made it clear that there are many, many more exorcists than just Natori, although at this point in the series it's still not clear if Midorikawa plans to do much with them. The egg story was just “meh.”
(Original review posted on A Library Girl's Familiar Diversions.)