Amasawa Rei was enrolled in Shirohato Park Institution during her childhood. When her parents died in an accident, she stayed at the institution and became friends with a boy. However, she has little recollection of her time there, including names and faces, except for their shared secret, which she feels may be darker than anticipated. Now attending Shirohato Academy with her former classmates, Rei is haunted by vague memories of her past. She is determined to uncover the truth about the secret and locate the boy. However, the biggest mystery remains: why can't Rei recall anything from her past?
