Details

Yu, a returnee student, transfers to Ai's high school. One day, a student appears on the playground, crawling on all fours-but no one reacts. Days later, a human pyramid forms, and students are forced by teachers to join. Though confused, they comply. Ai and Yu try to escape, but fail. At the sound of a whistle, everything returns to normal. Later, another whistle triggers students to march in unison, forcing Ai and Yu to flee.