Souko Morinaga  

, 守永 蒼子

It is said that Souko Morinaga inspired the creation of the Book of Friends by its young adult author, who is also known as a top-ranked exorcist. This is because during her meetings with Reiko Natsume, she suggested that youkai could be challenged to various games, duels, and "fights" in exchange for their names, which would help Natsume pass the time when he couldn't spend it with other humans.