Nagisa is a high school student with a typical daily routine, including rushing to school and meeting up with friends. However, her morning is disrupted by a woman in a bizarre uniform who seems to be staring at her. Later, Nagisa notices a ball moving on its own and flinging itself at her window, shattering the glass. After the commotion, Nagisa sees a mouth full of teeth close to her face, but when she screams, everything returns to normal.