It's October and the heavens themselves appear to be crying.
The rainy season is not the only thing bringing down everyone's mood in the rural boarding school of Miatori. A mysterious assailant stalks stray students in the shadows, with no other apparent goal but to draw blood. The circumstances make it seem something downright supernatural is involved.
As a power struggle behind the school's administration keeps the police outside, Mikoto Kiyoharu decides to take the law into her own hands. But the devilish plot she begins to unravel might prove too much for even the adults to handle...