The protagonist wakes up in a dim and dreary room and has lost all memories of herself. Her left arm is mysteriously paralyzed, as she is unable to move it. There is a cellphone left in the room and it rings. On the other line is a child’s voice who calls herself Chizuru. “You are Maria Kamishiro. You are a participant in this experiment. I will tell you your role. ”Chizuru tells Maria in a mechanical tone of voice that if she succeeds in this “experiment,” she will be released, and then suddenly hangs up. However, there is no indication of when the experiment will begin. Or perhaps it is already beginning? At any rate, it is clear that you have gotten dragged into an unusual situation. While Chizuru’s goals are unclear, you have to find a way to escape from this place as quickly as possible.