As industrialization sweeps across the world, a malevolent force emerges that cannot be vanquished until its heart, protected by an iron shell, is pierced. This creature infects humans with its bite, creating aggressive and undead beings known as Kabane. In the remote eastern island of Hinomoto, residents have constructed shelters to protect themselves from these horrors. People can access stations via a locomotive called Hayajiro powered by steam, facilitating trade between them. Ikoma, a boy living at Aragane station who helps build Hayajiro, devises his own weapon: Tsuranukizutsu, aimed at defeating the Kabane menace. One day, as Ikoma waits for the perfect moment to use his weapon, he encounters Mumei, whose inspection is excused due to her sensitivity towards Kabane creatures. At nightfall, Ikoma reunites with Mumei while observing Hayajiro out of control. The locomotive staff has transformed into these undead beings. With Hinomoto's station under assault by the Kabane threat, Ikoma sees his opportunity.
As the immortal Kabane monsters ravaged Aragane Station, young steamsmith Iko...