They succeed in escaping through the ventilation shafts, but Nobuo is left behind in the darkness and is never seen again. He and Ako soon escape after the tunnel starts collapsing and, incredibly, lava begins flowing in it. Despite getting stabbed in the shoulder, Teru manages to overcome and defeat Nobuo before almost killing him with a rock. In the chaos, amidst falling rocks and choking steam, Teru notices Ako being chased by a crazed Nobuo and comes to the girl's rescue. In the ventilation shafts, Teru is suddenly hit by a powerful stream of contaminated water, which saves him from a previous cave-in that almost buries him alive, and the shaft collapses while the tunnel is rocked by more powerful tremors. He kidnaps Ako and almost rapes her, but she manages to escape. Meanwhile, Nobuo becomes deranged, paints his body as if he was a primitive savage, and mutilates the corpse of a teacher thinking he's still alive.
After days pass with no sign of rescue, Teru tries to find an escape route and ventures into a partially collapsed ventilation shaft. Nobuo's mental state deteriorates to the point where he claims the wrecked train for himself, forcing Teru and Ako to build a makeshift shelter outside in the tunnel. While they find temporary shelter in the dining wagon, Nobuo gives in to fear and declares that "something" is lurking in the tunnel with them. Teru treats Ako, who wakes up after several days. Wandering the wrecked wagons of the train, he finds Nobuo Takahashi (高橋 のぶお), a highly unnerved boy who apparently was being bullied at school, and Ako Seto (瀬戸 憧子), who is unconscious and wounded. Knocked unconscious during the derailment, Teru reawakens to find, much to his horror, that all of his teachers and classmates have died in the crash. Soon after entering the tunnel, a powerful earthquake derails the train and blocks both sides of the tunnel with rubble. Just before his train enters a tunnel, Teru briefly sees something in the distance, though he doesn't understand what he saw. Teru Aoki (青木 輝), the main protagonist, is riding a train to Tokyo after a school trip.