Ep 5. Inescapable Darkness

As dawn approaches, Ikoma and Mumei make their way through a dark tunnel to escape the impact zone of a kabane. Ikoma's steam gun is in danger of overheating, causing him to panic but he manages to fix it with Mumei's help. They successfully make it out of the tunnel but are ambushed by a group of kabane in a forest. They fight them off, but during the commotion, Mumei notices her necklace is missing, which contains an object that appears to be sentimental to her.

Ikoma and Mumei make their way to a nearby station and discover two survivors, a woman and her child, being besieged by the kabane. Ikoma decides to help them by creating a prototype weapon, but he needs a piece from the steam engine on the train. The group starts the engine up, but they realize they have attracted a horde of kabane in the process. Mumei jumps onto the roof of the train to fight off the kabane, while Ikoma sneaks around to get the piece he needs.

However, a group of humans from an organization called the Hunters arrive and start shooting at Mumei, believing she is a kabane. Despite the misunderstanding, Mumei quickly defeats them, but one manages to shoot her with a special bullet that incapacitates her. Ikoma arrives with the piece he needs and uses it to create a new weapon, but he is too late to save Mumei.

The group continues to fight off the kabane and manage to escape, but they are left with the realization that they are constantly surrounded by inescapable darkness. They also find out that the mysterious organization, the Hunters, are after Mumei for unknown reasons.