You wake up with no memory in a sealed tower with six girls and a corpse. One of them killed the man next to you, and you have to figure out which before trust collapses entirely. The zombie apocalypse outside stops mattering the moment the real threat becomes the people you're trapped with.
Civilization crumbles under a zombie plague, leaving survivors to fend for themselves in the wreckage. Mikoto Amano regains consciousness in an unknown location with a blank slate for a past, rescued by six girls who share the safety of Tokyu Kabukicho Tower. The fragile sanctuary shatters when a man brought inside alongside Mikoto turns up dead. One of the girls is responsible, but which one remains hidden behind conflicting testimonies and suspicious silences. Trapped within the sealed building, the group faces an impossible choice: execute justice among themselves or risk infection from the undead outside. As they interrogate each other and piece together fragmented alibis, deeper secrets emerge. Old grudges surface. New allegiances crack. The mystery of the murder becomes inseparable from the mystery of Mikoto's own forgotten identity, forcing these survivors to question whether they can truly trust anyone when survival strips away their humanity.