Ever since she was three years old, Kaori has lived in a bookstore where the boundaries between the mortal realm and the spirit realm are blurred. Her adoptive father, who lives with her in this magical space, is a spirit himself. One day, Kaori comes across a bleeding young man who has stumbled into the spirit realm just as she did when she was a small child. Though the young man is an exorcist who has vowed revenge against all spirits, Kaori decides to embrace kindness and help him find his way back home.