Having grown accustomed to encountering youkai through the Book of Friends, which contains the names of youkai sealed in contracts by his grandmother, Reiko Natsume, Takashi Natsume gains a better understanding of youkai, Reiko and himself. Though sought after by both youkai and exorcists as a powerful tool for controlling youkai, Natsume wishes for nothing more than a peaceful daily life, constantly disrupted by these experiences. If Natsume is to escape this torment, he must delve deeper into the world of exorcism and the Book of Friends, and learn to open his heart to those who might help him.