Mischevious Nobara and good-girl Kotori were identical twin sisters. After their father's death, they lived with their grandmother and mother, respectively, but tragedy struck when Kotori was murdered while they had switched places. Nobara was filled with immense guilt and her mother's hair turned pure white due to the loss of her precious daughter. In an effort to protect her grieving mother, Nobara decides to assume Kotori's identity and live as her.