Formerly a covert spy under the shogunate, ronin Azami Onijuro and his carefree companion, ronin, journeyed along the Kiso Highway. As they approached the Echizen Domain, they encountered a woman named Osode. Recognizing Onijuro's formidable skills, she asked for his help as she was on her way to Owari. Osode, the daughter of the second-ranking retainer of the Katsuyama Domain, carried a blood-sealed letter that served as evidence of a conspiracy involving the assassination of the domain lord by the Deputy Chief and the lord's younger brother. Onijuro's group becomes a target and is chased after by the chief retainer's top enforcer.