The story takes place in Hinomoto, a fictionalized version of Japan, where railway travel long served as the primary mode of transportation. Every locomotive was paired with a humanoid control module, known as a RailRoad, to assist the train operator. However, many rail lines were discontinued due to the growing popularity of 'aerocrafts,' a safe and convenient aerial transport method. Consequently, their accompanying RailRoads fell into a deep sleep. Soutetsu lost his entire family in a rail accident and was adopted by the Migita household, which operates a shochu brewery in the city of Ohitoyo. He returned to his hometown to prevent potential water pollution that would result from accepting a proposal to build an aerocraft factory nearby. He accidentally woke up the RailRoad Hachiroku and became her owner. For their own respective purposes, they agreed to help locate her lost locomotive, with assistance from his stepsister Hibiki, the town’s mayor, the local railway chief Paulette, and others.