Natsume discovers that the heirloom Book of Friends that his grandmother, Reiko, gave him possesses the names of the spirits she defeated and bound to her will.

Natsume decides to return the names of the yokai with the help of his new bodyguard, Nyanko-sensei: a small yokai named Tsuyukami comes to get his name back, but the page with his name is stuck to the next page.

A yokai who lives in Yatsuhara comes to Natsume to ask him to capture a human; a classmate who recently moved to Yatsuhara named Tanuma starts asking about Natsume.

Natsume and his classmates decide to go ghost hunting at the old school building; Sasada has a favour to ask of Natsume.

Natsume finds a train ticket among Reiko's belongings and meets a hairy yokai named Santo, who is waiting for Reiko at the station; Natsume learns more about Reiko's feelings when he gives Santo his name back.

Natsume finds a town that had been submerged in water; Natsume gets possessed by a yokai and falls unconscious.