Watanabe Satou is an ordinary schoolboy from the small provincial town of Terawata. One day he discovered that his classmate Yusaki Rin was missing. Strangely enough, no one in the class remembered her. Yusaki was always so cheerful and upbeat, and Satou couldn't believe that everyone had just forgotten about her. As he investigated, Satou began to notice strange things. His own childhood memories seemed to disappear, and he couldn't remember how he spent his time as a child. Satou realized that it was up to him to penetrate the mystery of erased memories to find answers and save his friend before she finally disappeared into the shadows of the past.