Suzune, who was adopted as a baby and never knew her birth parents, spends a summer with friends at a holiday home in Nagano. When Aya, the five-year-old daughter of a family close to them, disappears, a suspicious letter six years later leads Suzune toward the mystery of her origins and of 'Blue Snow.'

A full-length mystery in which a girl's disappearance and a single letter uncover truths hidden in a family's past.