The people are tormented by the Onikigumi, a group of thugs who act as pawns for the shogunate, collecting money in a manner similar to extortion, and the existence of the mysterious "Iron Machine Hunters" who target the iron machines of these evildoers has become a hot topic of conversation. The story begins when wanderer Kotetsu Kisaragi meets Suzuno, the daughter of an iron machine smith, and witnesses the evil deeds of the Onikigumi, who threaten her home.

(Source: Gundam Wiki)