On the small, unremarkable island known as Sheeptop Island, a massive prison stood tall—one that held only the most vicious criminals. Officer Takamiya, stationed there, lived a quiet and peaceful life… until the blaring alarm of a prison break shattered the calm. As panicked islanders fled, they were brutally slaughtered one after another. With the situation spiraling out of control, the police unleashed their final trump card. A high school girl named Yuka—also known as “The Thirteen-Killer.” On an island where the survival rate is zero percent, can this merciless girl hunt down every last monster? A brutal survival suspense that will leave you trembling— soaked in blood, driven by madness, and ending far beyond all expectations.