Takashi Natsume can see the spirits and demons that hide from the rest of humanity. He has always been set apart from other people because of his gift, drifting from relative to relative, never fitting in. Now he's a troubled high school student who has come to live in the small town where his grandmother grew up. And there he discovers that he has inherited more than just the Sight from the mysterious Reiko.

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?