Oedo is a lively town where various people live. Yuta, who is training as a blacksmith, wants to help people but is weak. One day, he meets the inventor, Hiraga Gennai. Gennai gives Yuta the steam-powered armor that he invented which increases the power of the wearer by several times. Meanwhile, the evil secret society Shimavaran, led by Amakusa Shiro, is approaching the town of Oedo. Yuta dons the steam powered armor and confronts Shimavaran! What will the fate of Oedo be?