Saya Otonashi is a seemingly ordinary girl living a mundane life with her adoptive family in Okinawa City. In fact, her only peculiarities are suffering from anemia and being unable to remember any of her life beyond the previous year. However, Saya's forgotten past quickly comes back to haunt her—one night, she is attacked at school by a creature that feeds on human blood. Just when all hope seems lost, a mysterious...