In the age of peace, Oedo is a bustling town where all kinds of people roam. Yuta a blacksmith in training is an ordinary man that likes to help people, but he isn't known to be strong. One day at an endurance contest, he meets Hiraga Gennai, the local inventor.Gennai gives Yuta a steam armor he invented, which increases the wearer's physical strength. Meanwhile, the town of Oedo is under the spell of the Shimavaran, a secret society led by Shiro Amakusa! Yuta with his new steam-powered armor becomes the one to face the Simavaran! What will be the fate of Oedo!