Publisher Marketing:
The strange kid at school, the odd woman in the apartment building, the troublesome man at work. Such people exist everywhere, in everyone's lives. All it takes is a word for it to start. An unsettling question, a bizarre remark, or even a kind apology. Once their hooks sink in, the cracks form. Darkness floods into the recesses until nothing else remains, and then...Sirens, screaming, dull thuds on the pavement. They have always existed. They just are. And when they show up, people die.

After a quiet boy named Kaname joins the class, Mio reaches out to him, hoping to help the odd boy settle into his new environment, but when he starts showing up at her house all the time, she begins to be frightened of some nameless wickedness.