It's Shigeru's birthday and Touko has asked Natsume to buy some strawberry shortcakes to celebrate. However, Shibata, an old classmate of Natsume's, finds him and asks for his help. He remembered Natsume used to say weird things, so he wanted to know if a girl he's been seeing is real or not. When Natsume meets the girl, Murasaki, she seems normal. He reassures Shibata that she is a human. Natsume later has a vision that reveals her to be a tree youkai with intention to eat Shibata. Natsume tries to warn Shibata, he refuses to listen and accuses Natsume of lying. Natsume tries to talk to Murasaki, but she does not waver. It is then revealed that although she had initially planned to eat Shibata, she fell in love with him as they spent time together, and because her tree has been cut down, she will die soon anyway. Shibata receives a note from Murasaki just in time for the two of them to spend her last moments together.

Natsume accidentally bumps into a woman with blood covering her body. He follows the bloody footsteps that the woman left and discovers a small house. When he opens the door, he sees badly injured youkai. There is someone killing youkai for blood, and with the help of Natori, Natsume tracks down who he believes to be the murderer: Matoba. However, Matoba captures him.

Natsume finds out who's been stealing the youkai blood: the exorcist Matoba Seiji. He investigates with the help of Natori, but is captured by Matoba's servant youkai. Matoba is willing to sacrifice any number of youkai for his own ambitions. He tells Natsume why he's gathering blood: to release the seal on a powerful youkai. Natsume learns that there are people who treat Youkai in a totally different way than he or even Natori.

Natsume encounters some strange, monkey-mask wearing demons while out in a forest. They want the book of friends, and start physically threatening him until Natsume is saved by Nyanko-Sensei. Later on, Natsume encounters the demons again and is captured by them, and brought to their forest. Meanwhile, Nyanko-sensei learns some interesting things about the forest the monkey mask demons live in. Running away from the demons, Natsume and Nyanko-sensei are unintentionally saved by an exorcist - Matoba! Not wanting to confront him, Natsume runs again but gets lost in the woods, and stumbles upon a house... belonging to the Matoba. Both he and Nyanko-sensei are captured, but manages to escape and find each other, though being lost in the house. The episode ends with Matoba finding Natsume saying, "It's been a long time, Natsume Takashi-kun.

Natsume and Matoba talk, but when the conversation doesn't go the way he wants, Matoba orders Natsume to be put in a cell. Natsume escapes with the help of Nyanko-sensei. Along with his other demon companions, Natsume helps the monkey-masked demons living in the forest.

Natsume is trapped in a bottle by a youkai to be offered to another named Omibashira. Nyanko-sensei transforms into Natsume and goes around his school to ask his friends about Omibashira, but gets Tanuma involved. Tanuma is attacked by one of the youkai that trapped Natsume and loses him, but as he runs through the forest looking for Natsume he finds a mansion behind the school. When Tanuma is suddenly able to see the youkai walking up the steps to the mansion, he is found out by a youkai with a bag over its head.

Natsume is saved by Tanuma and the two escape from the banquet hall with the help of Natori, who was disguised as a youkai. Tanuma is drawn more into the world of the youkai and experiences it first-hand, which greatly worries Natsume. Blood marks are found all around the mansion and Natsume's fears come true when Tanuma is attacked by Omibashira, but is protected by a stone Natori gave him. After Natsume helps Natori seal Omibashira everyone is able to escape the previously sealed exits. Promising Tanuma that he'd tell him his complaints at school the next day, Natsume finally arrives back home.