This volume starts with the tale of Natsume being asked to involve himself in something of a professional battle between two yokai, but the real gem of this volume is the second story - Natsume goes to visit Natori and ends up being roped into a competition where exorcists are looking for the hidden library of a yokai researcher.
In an earlier volume, Natori accidentally overheard a yokai mention the book of friends. Until this point, Natsume had been keeping it a secret from everyone out of a perfectly justified (I believe) fear that people might try to take it from him and use it for evil things. Since that time, it's been somewhat unclear what Natori intended to do with his knowledge, and there were some signs that it might not be completely what Natsume might want to hear. But in this volume, it comes to a head, and the two have to clear the air about that tension. I very much enjoyed it (it helped with the story itself, which was not badly written but which did feel a bit like it was retreading old ground, if only to show how much Natsume and his circumstances have changed).
The final story in this book actually looks at a completely new character, a young woman who charges ahead in life but who crosses paths with Natsume because - as you could guess - a yokai. It's again a story type we've seen, but the character is so fun that I was willing to forgive it. :)