Volume 1 Introduction: In a small town covered in snow, a bizarre murder takes place. The victim is a high school girl, Mako Igarashi, who was mutilated. The murderer, Mizuki Aikawa, a classmate, turns herself in to the police. Mizuki confesses to the crime, but there is something strange about her...? This is a realistic suspense about the "secret" of two girls fighting against the darkness!
