At school, Aoi notices how different things are compared to a normal high school. The rules are bizarre: students mustn't talk to one another before 9:00 am, everyone wears watches that beep in unison, and there are cameras in every classroom corner. The principal, Mr. Nakahara, has an unnerving aura, and today, he holds a sudden assembly. He reinforces strange rules — "Stay inside the lines when walking the halls" — that make Aoi feel like the school is more prison than education. Aoi's classmate, Rei, passes her a note in class: "Meet me at lunch. We need to talk."