Accompanied by his spirit companion Nyanko, Takashi Natsume continues his quest to return the names of spirits from his grandmother's Book of Friends. A chance encounter with the spirit Monmonbou triggers memories of his grandmother, leading Takashi to investigate the town where she once resided. Making new friends in Yorie and Mukuo, Takashi delves deeper into his grandmother's past. Meanwhile, Nyanko's hunger leads to a peculiar discovery of a Spirit Seed that transforms him into three beings. As they search for a remedy, Takashi and his companions unravel the town's hidden mysteries, revealing more than they bargained for.