Zerozaki Soushiki no Ningen Shiken

Iori is an aimless high school girl who lacks direction for her future and has a persistent habit of fleeing from difficult situations. Her ordinary life shatters one morning when she is ambushed on her way to school by unsettling individuals with hollow, dead eyes. Just as the situation turns dire, she is rescued by a mysterious, long-haired stranger. The danger, however, does not end there. Later that same day, her schoolmate Jion succumbs to the exact same murderous compulsion, turning violently against her. To her own astonishment, Iori discovers a hidden capacity to defend herself against his sudden assault. In the aftermath of this harrowing encounter, the enigmatic man from the morning reappears. Introducing himself as Zerozaki Soushiki, he presents her with a bizarre proposition: an invitation to become his little sister. Thrust into a terrifying and incomprehensible world, Iori must now confront the reality of what she has become entangled in and determine whether she possesses the strength to survive the irreversible transformation of her life.