Set in a world where, no matter what the circumstances, everyone who kills someone is themselves sentenced to death. Those on death row are imprisoned in the "Six Prison Districts," where a strange economic system has emerged. One day, a steam train sends a new batch of prisoners to one such district, as it does every day. A man named Yūshin, who calls himself a chaplain and bears priestly garb, also disembarks, and encounters a man who bears a sword that is called Kunoji.