Mayumi is a girl who lost her parents in a car accident; unable to deal with the overwhelming sadness, hatred and anger, she wishes only to be able to stop feeling altogether.

Five years later, the now 18-year-old Mayumi's sister is the first victim in a series of bizarre incidents that involve people receiving text messages indicating a certain body part, immediately after which said body part is removed - painlessly and without blood loss - from their body and disappears completely.