The player assumes the role of Maria Kamishiro, who awakens in an unknown location without her memories and with her left arm paralyzed. A mysterious person named Chizuru forces her to engage in a strange experiment in order to escape.

While trying to find a way out, Maria meets with Eito Ginjo and Jun Yagi, two survivors who are also captured and locked up in the same location. They're being stalked by hostile masked people from the dark.