Nagisa is a schoolgirl with typical schoolgirl habits: she wakes up late, rushes to school, and meets friends along the way. One morning, Nagisa encounters a woman in a strange uniform who seems to stare at her, unnerving Nagisa. Later that day, while staring out the window, Nagisa notices a ball bouncing on its own. It flings itself toward her window seat, shattering the glass but not harming her. Turning back to the front, she finds a gaping mouth bristling with teeth inches from her face, with no one else around. She screams, and the world returns to normal, leaving her standing as the center of her class's curiosity... why did she scream?