In a world devastated by a zombie pandemic, the protagonist, Mikoto Amano, wakes up in an unfamiliar place with no memory. She is taken in by six girls: Ranna, Lili, Yuu, Fumika, Murumuru, and Rumina. However, their peaceful days are suddenly shattered when a shocking event occurs—the man who was rescued alongside Mikoto is brutally murdered. The killer is among them, and the next target could be anyone...

Set in the Tokyu Kabukicho Tower, the story unfolds in this now sealed-off high-rise, where mysteries and secrets attack one after another. As bonds of friendship start to form among the girls, will they be able to uncover the truth behind the incident?