A "tsukumogami" is a Japanese folklore object that has obtained a soul and has become living and self-aware. The mature "tsugumomo," who have matured over many years of harmony with their owners, and the aberrant "amasogi," premature spirits that are only created to grant the destructive wants of some individuals, are the two varieties of tsukumogami. After his mother's death, Kazuya Kagami has never left home without his mother's obi. He keeps it secure with him at all times, whether at home or at school. When a wig amasogi assaults him one day, he almost loses his life. When all appears to be over, his prized obi defends him by morphing into a lovely young lady. Kiriha, a tsugumomo owned by Kazuya's mother, introduces herself.