After the train crash, Nobuo, Teru, and Ako are the only survivors. Loosing himself in the desperation of being alone and the darkness that consumes the place, completed with the help that never comes, Nobuo gets crazier by the minute.

Spoiler

Convinced the darkness has the form of a human and that he must deliver a sacrifice, he kidnaps and paints Ako in the blood of his dead teacher, preparing to deliver the final blow and appease the shadow in the darkness.