Many of Natsume's problems with the local yokai stem from his grandmother, Reiko. When she was his age, she went around challenging yokai, and when she won she sealed their names in her Book of Friends. But lately Natsume has been learning that Reiko was more than just a cruel conqueror. Will he ever know the full truth about his grandmother, and will yokai be the ones to help him discover it? Rated: T