Takashi Natsume has always been able to see Yokai, and because of that, he lived a very hard life. His inability to pretend he wasn't seeing what he saw had him being shuttled from relative to relative, each one afraid of what they saw as his strangeness, and other children teased him for his eccentricities and called him a liar. But then, he was taken in by distant relatives who actually wanted him, and they treated him as they would have their own son... had they had one. Grateful for their love and kind attention, Natsume was determined not to make these two suffer because of his strangeness and managed to conceal what he saw.
But Yokai continued to attack him, thinking him to be his grandmother, Reiko, who had the same abilities. But unlike Natsume, who only wants to be left alone, Reiko blamed the Yokai for how others treated her, and challenged them to contests, taking their names as she won, and binding the pages with their names into a book, The Book of Friends. Even though the Yokai eventually realized that Natsume was not his grandmother, they wanted the Book, because it was a source of power. Finally, Natsume stumbled on a Yokai named Madara and accidentally freed him. As a boon, Madara agreed to be Natsume's bodyguard and teacher, in exchange for the book when Natsume dies. He now watches over Natsume in the form of a ceramic Maneki Neko, or "Lucky/Beckoning Cat" statue, which others see as a real cat, and whom Natsume calls Nyanko sensei.
In a thicket near his house, Natsume discovers a flock of crows attacking what looks like a kitten. But when he dives in to rescue it, he discovers that it isn't a kitten after all, but some kind of Yokai fluffball with eyes. Thinking it might attack him, he tosses it away and runs home, only to find that it has hitched a ride along with Nyanko-sensei. He gets a better look at it, and decides it's cute, but when he tries to see its injuries, it goes wild, bouncing around like a ball. Natsume catches it, only to discover that its fluff can turn sharp as needles. He tells it to calm down, that it is safe here, and it slowly calms down. He tends its injury with some Yokai medicine he once needed and tells the fluffball that it can stay with him for the night, but it needs to leave in the morning.
The next morning, he releases it back into the forest, only to catch a glimpse of it at school. But it isn't alone. There are lots of them. When he gets home, he gets attacked by a Yokai named Amana, whose name he returned the day before. She accuses him of being a thief and commands him to give "it" back. It turns out she lost her ring, and if it isn't returned to her in three days, she will burn down his house and everything in it. They look for the ring with no luck and then decide that it may have accidentally been picked up by the fluffball. Natsume asks for help from the Yokai he knows, and Hinoe tells him that the puffball is a Karu, a rare Yokai that travels in groups. Natsume finds them and asks about the ring, and they attack him, injuring him further, but are driven off by the other Yokai.
Hinoe tells him that this is the way the Karu are- that alone, they are shy, but when grouped together, they are strong, and can eat other Yokai, even fairly powerful ones. They continue searching, but the Karu are gone. Later that night, Natsume tells Nyanko-sensei that his wounds still hurt- Karu spines are poisonous. But when he wakes up in the middle of the night, he sees a spot of red on his sheets. Blood? No, it red lotus seeds- well known among the Yokai for drawing out poison. The Karu brought it.
But when Natsume is about to ask about the ring, another Yokai shows up, and the Karu gets overexcited again and once again injured Natsume. When he finally gets it to calm down, it flees- obviously feeling bad for having once again injured Natsume without meaning to. But can Natsume find the Karu again and get the ring back for Amane? And will she believe him that he didn't steal it, merely retrieved it for her?
Then, Natsume is approached by a Yokai asking for help in freeing its trapped friend. But when he does so, the Yokai tells him to run. Natsume is too confused to run and is grabbed by a group of Yokai in strange masks, who demand "The Book of Friends". They want it for their leader, but then, Natsume, in the process of being rescued by Madara, aka Nyanko-Sensei, finds himself on the run from Mr. Matoba of the famous exorcist family.
He and Madara get separated, and Natsume sees one of Matoba's "created by spell Yokai" grab one of the masked Yokai and put him in a jar to contain him. Then, the one of the spell-Yokai grabs him as he tries to find Nyanko-sensei and hides in a small shrine. The Spell Yokai takes him to Matoba, who is intrigued by Natsume and attempts to question him about who he is and his abilities. Natsume remains silent until Matoba decides to threaten the jarred Yokai, and even then, he tries to conceal as much as possible.
Matoba asks him about his grandmother, Reiko, and Natsume reveals that he never really knew her, and certainly never met her. But he doesn't know about the "Book of Friends", and none of his captured Yokai seem to have enlightened him about it. Natsume wants to leave, but Matoba doesn't want to let him. Can Natsume find a way to get away from Matoba with the Book of Friends, and will he blame the masked Yokai who originally kidnapped him for his capture? Will Matoba learn about the Book of Friends, and just how dangerous will he be to Natsume in the future?
The book ends with another story about Natsume from a girl who knew him at his last school. While she doesn't understand him at the beginning of the story, she comes to realize that there is something special about him that the others just don't get. But can she enlighten them to think better of him, or will she become an outcast on her own just for defending him?
I really enjoyed this book. There are two stories in here, but the first one had an exceptionally beautiful ending, and the second presages more bad news for Natsume. Now, Matoba seems to be interested in him, and by the end, he might have learned about the Book of Friends. This is especially bad when you see how powerful Matoba is already. He may think that his Yokai can't stand up to the friends of Natsume, but his attitude towards Yokai means that the Book ending up in his possession would be... bad. Very bad. Probably World-Endingly BAD.
The only thing I see being able to save Natsume at this point is that Natsume counts Yokai as his friends. Matoba's Yokai are all his servants, and forced into that service as well. Slaves don't have much reason to fight for their master. Not fight well, in any case, while a friend will defend you to the utmost. But I am alarmed at the thought that Matoba will consider Natsume someone to be fought and tamed, or brought forcibly to his side, and he already knows that Natsume can be controlled by threatening a relatively harmless Yokai with death or torture by spells- that gives him a leash and a goad to controlling Natsume, at least for a while. I can only hope that if he is captured again by Matoba for some kind of final showdown, that all the Yokai whose names he has returned from the book will be rounded up to defend him.
I love this series so much! Each book is slightly different, and Natsume's attitudes towards Yokai have changed and grown with each one. And the danger to Natsume has also grown, but I hope that my fears won't come to pass, even though I am not so sanguine about that hope. Highly recommended.