15-year-old Aya Kito was an ordinary girl, the daughter of a family who works at a tofu shop, and a soon-to-be high schooler. However, odd things have been happening to Aya lately. She has been falling down often and walks strange. Her mother, Shioka, takes Aya to see the doctor. How will Aya react when told about her disease? And how will Aya live from now on?