Takashi Natsume has become accustomed to meeting youkai through the Book of Friends, a tome that lists the spirits his grandmother, Reiko Natsume, has bound with contracts. These encounters enable him to gain a deeper understanding of the youkai, his grandmother, and himself.
The Book of Friends is a powerful tool for controlling youkai; it attracts both spirits and exorcists. Natsume simply wishes to live a peaceful daily life, yet these experiences continually disturb him. To end this torment, he must investigate the book and the world of exorcism further, and learn to open his heart to those who can help him.
