Tanuma's father leaves on a trip and a strange youkai invades his house, spreading miasma that makes all the nearby youkai suffer. Natsume tracks it down and discovers that the noxious youkai was once a resident in an all-youkai village. A portal had opened for a short time during a human ceremony that he had taken his sister to watch. However, they became trapped in the human world, and his sister died. After returning to the old temple where the ceremonies were held, the portal opens and he returns home.

Natsume is invited to go to a pottery classroom with Shigeru. It's being held in an inn where he once stayed. When he goes there, he meets an old friend: the young fox child he once saved.

Natsume spends time playing games with youkai he has befriended. He remembers games he was left out of as a child.

Natsume befriends a small fluffball youkai.

Natsume, accompanied by Nyanko-sensei, set out to visit his old home. He visits a relative to pick up the key to the house, but is being followed by a youkai who wants him to draw a mouth for it. He leads the youkai away from the home of his relatives and Nyanko-sensei drives it away. When the two get back on track to finding the house, Natsume is suddenly attacked by the youkai and becomes lost in old memories.

Nyanko-sensei falls into a well and discovers that there is a barrier inside it, as well as Nanase, Matoba's assistant. She is looking for a certain stone with a youkai she had sealed in it, and tells Nyanko-sensei the story of how she met the youkai to pass the time.

Natsume finds a letter addressed to him from Matoba. Walking in the forest, he loses it when an amateur exorcist seals a yokai in a pot. Noticing the weak seal, Natsume and Nyanko-sensei take it to Natori's condo to re-seal it. When Natsume returns home he sees Matoba and learns the letter was a request for Natsume to attend a meeting of strong exorcists to weed out the person who has been targeting exorcists.

Tanuma invites his friends to an inn run by his relatives. While sweeping outside, Tanuma is greeted by an old woman named Ito-san. Natsume learns that Ito-san is a yokai that serves the Mizunagi shrine by protecting the mountain festival. Ito-san has come into the inn because another yokai has stolen the festival's white mask and has disguised itself as an inn guest. Natsume finds the yokai who stole the mask for the festival's power, and Ito-san exorcises her. Ito-san warns Natsume to keep her identity a secret until after the festival is over so she can complete the festival. Natsume says he will tell no one she is a yokai so she can stay in this town as long as possible.

Natsume's old classmate Shibata (from "False Friend" / "Itsuwari no Yūjin" (偽りの友人)) calls. Natsume visit Shibata together with Tanuma, where Shibata tells them about the "Doll Mansion of Sotogi". A youkai from the mansion later attacks them.

Natsume is surprised when a youkai comes to seek Reiko in gratitude. Years ago, the youkai's to-be-bride received freedom from her help, and now is about to be wed. They invite Natsume to the wedding.

A competition is opened to search for a famous researcher's sealed room. The prize are his research books, and many exorcists are gathered. Natori is invited, Natsume wants to help as this might mean finding something that might let him find information about the Book of Friends.