Ishinomaki Aoba is a talented street musician. She really loves her best friend, Machi, who is an aspiring pianist and one day aims to join Aoba in her performance.
One day while talking to each other on the phone, Machi suddenly goes silent. Aoba, fearful about her friend's welfare, rushes quickly into school - only to find her unconscious in a pool of her own blood.
Machi lies in hospital, unconscious. Her life is safe, unfortunately, her hands are not. As an attempt to go save her hands, Aoba relied on a book about black magic and tried a ceremony to return to the past.
The ceremony succeeded - but instead of sending her a few hours back, she got sent 17 years into the past instead...