Takashi Natsume can see the youkai that ordinary people cannot, and he carries the Book of Friends, a ledger his grandmother Reiko filled with the names of spirits she bound. This sixth season continues his routine of returning those names to free the youkai who come seeking them, with his guardian Nyanko-sensei at his side. New encounters draw Natsume further into the world of spirits while he keeps building the everyday human ties he never had as a child.