Natsume's Book of Friends: Spirit Book Keychain This is a fun keychain from the anime and manga series - Natsume Yuujinchou or Natsume's Book of Friends! The golden colored charm is a small 1.25-inch replica of the book passed on to the main character, Takashi Natsume. Inside the book are the names of spirits his grandmother sealed with a contact. Carry your own Book of Friends!