The Fusoujou was Hayatani Station's Hayajiro and was used shortly after the fall of the station, to presumably transport survivors and supplies to the nearest station which happened to be Aragane. Along the journey though, somehow the Kabane managed to hijack the entire train and ram it into the west gate of Aragane causing the Kabane to swarm the city and eventually overrun it.
Known Members Aboard
Former Hayatani station survivors.
Yukina and Sukari met the son of one of its engineers at Shitori station.
The engine's 3d model was recycled for multiple Hiyajiros owned by defense groups. Examples include: 3 defending trains on a multi-story railway section in Kongokaku, and another being used as a defense train, by the Allied Forces in the Unato Movie.