Natsume Takashi has the ability to see spirits, which he has long kept secret. However, once he inherits a strange book that belonged to his deceased grandmother, Reiko, he discovers the reason why spirits surround him. Containing the names of these spirits, a binding contract was formed between the spirits and the owner of the book. Now, Natsume is determined to free the spirits and dissolve the contracts. With the help of a spirit cat, his days are filled trying to return the names to these spirits.

[Source: Anime News Network]

Natsume Takashi, with the help of Nyanko-sensei, continues his adventures to free spirits contracted by his grandmother Natsume Reiko in the "Book of Friends".

[Source: AniDB]

Natsume Yuujinchou San is the sequel to Zoku Natsume Yuujinchou and is the third season in the Natsume Yuujinchou series.

Natsume Yuujinchou San follows Takashi Natsume, a boy who is able to see youkai. Natsume and his bodyguard Nyanko-sensei continue on their quest to release youkai from their contracts in the Book of Friends.

Natsume comes to terms with his ability to see youkai and stops thinking of it as a curse. As he spends more time with his human and youkai friends, he realizes how much he values them both and decides he doesn't have to choose between the spirit and human worlds to be happy.

[Source: MyAnimeList]

Takashi Natsume continues to return the names of the spirits that have been written in the "Book of Friends" he inherited from his grandmother, Reiko Natsume. While Natsume is still aided by the chubby Nyanko-sensei, he's now helped by some of the friends he had made in his journey; be it human beings or spirits. As he becomes closer to both, Natsume faces the inevitable question of the sides he has to take especially when there is a conflict between the two.

[Source: Anime News Network]

Takashi Natsume has been able to see youkai, Japanese monsters, his whole life. He inherited a book of youkai names from his grandmother, Reiko. These names give their owner power over the youkai, so he and his self-proclaimed bodyguard "Nyanko-sensei" spend their days returning them to their original owners. As Natsume finally finds a place where he feels welcome, he meets and says goodbye to new Youkai...

[Source: Crunchyroll]

New original video anime on Blu-ray Disc and DVD which will reunite the cast from the four television anime series.

Natsume Yuujinchou San follows Takashi Natsume, a boy who is able to see youkai. Natsume and his bodyguard Nyanko-sensei continue on their quest to release youkai from their contracts in the Book of Friends. Natsume comes to terms with his ability to see youkai and stops thinking of it as a curse. As he spends more time with his human and youkai friends, he realizes how much he values them both and decides he doesn't have to choose between the spirit and human worlds to be happy.

[Source: MyAnimeList]

Special episodes included with the fourth and fifth volumes of the Blu-ray/DVD.

Precious days with kind friends. A beautiful yet fleeting story about people and spirits. Natsume Takashi had been able to see yokai ever since he was young and inherited his grandmother Reiko’s Book of Friends. He spends his days with his self-proclaimed bodyguard Nyanko-sensei and freeing the yokai that were bound to the book. Natsume continues to find ways to protect the precious days where he tries to find which path to follow through his connections with spirits and those involved with them and being helped out by friends who share the same feelings.

[Source: Crunchyroll]

Natsume has been busy, navigating between humans and Yokai when he coincidentally reunites with an old classmate, Yuki. It brings back painful memories of a certain Yokai. Meanwhile, Natsume also became acquainted with Yorie Tsumura, a woman in the memories of a Yokai whose name he had returned. Yorie knew much about Reiko, but now lived a peaceful life with her only son, Mukuo. Being with this family was comforting for Natsume, but apparently a mysterious Yokai has been lurking in their town.

On the way back from investigating, a “Yokai seed” that had latched itself to Nyanko Sensei drops into the Fujiwaras’ garden and grows overnight into a fruit tree. When Nyanko Sensei eats a fruit that is somehow shaped like himself, he suddenly splits into three!

Anime adaptation two popular stories from the manga: "Ishi Okoshi" and "Ayashiki Raihousha"

In "Ishi Okoshi," Natsume meets a small youkai called Mitsumi in a forest. Mitsumi is entrusted to wake up the divine youkai "Iwatetsu" from its deep slumber. Mitsumi weighs on Natsume's mind, so he sets out to help Mitsumi with his task.

In "Ayashiki Raihousha," a mysterious visitor appears in front of Tanuma. Nearly every day, the visitor visits Tanuma, talks to him a little, and then leaves. Natsume, who knows the visitor is a youkai, worries for Tanuma, but Tanuma enjoys these exchanges with the youkai. The youkai means no harm, but Tanuma's health slowly starts to deteriorate.

[Source: Anime News Network]

Natsume's Book of Friends Season 7 bonus episode included in the fifth Blu-ray & DVD volume.