センチネル

One month ’till Christmas Day. Students at Shigure High School are excited about it. Toru is also looking forward to it. But there is one thing that worries him: a girl who appears in his dreams. One night, the girl in his dream asks him, “Do you want to change your memories?” He recalls his childhood – he had lost his parents, and had decided to live with his younger sister. “Shall I change your memories?” Her mysterious offer turns into reality…