In the year 20XX, civilization has collapsed under a rampant zombie virus. A man in a white coat appears in a survivor community and announces, "We've discovered an antibody that will prevent zombification! He is found murdered. Attacks by "zombie believers" are on the rise all over the place. Rumors of a mysterious crazed strangler. Survivors disappear one after another, and a strange singing voice can be heard from underground every night.
The world has collapsed due to a zombie pandemic. The protagonist, Mikoto Amano, wakes up in an unfamiliar place with no memory and is taken in by six girls. However, a shocking incident occurs: a man who was taken in alongside Mikoto is murdered, and the culprit is one of them.
Set in the Tokyu Kabukicho Tower, mysteries and secrets unfold one after another within the now-sealed building. Will the girls, who have begun to form a bond, be able to uncover the truth behind the incident?