Regret is all

A close-up of a social studies textbook for 9th grade is shown, followed by a boy with spiky black hair standing in a schoolyard as a trail of light streaks across the sky above him. The scene shifts to a classroom where the boy playfully grabs another student from behind, then to the boy sitting alone by a window, and finally to a girl with long pink hair looking down a hallway before turning to face the camera.