A ronin named Azami Onijuro travels the Nikko Highway, he is being followed by the bounty hunter Daihachi and Yukata Danzen. He is pursued by his past as a covert spy under Lord Matsudaira. Due to certain circumstances, Onijuro betrayed him and became a wandering ronin. Ever since, he's been hunted by Matsudaira's subordinates and bounty hunters. After saving the tough and fiery woman Omom from yakuza trouble, Onijuro and his companions head to Akame-shuku (inn town). Here, a conflict brews between the Tsurugame family led by Genroku and the lawless monk group led by Tetsuzan, a former sumo wrestler gone rogue. Onijuro sides with Tetsuzan, while Daihachi and Danzen side with Genroku. This intricate web of allegiances and confrontations unfolds against the backdrop of the bustling post-town.

元隠し目付のあざみ鬼十郎が、彼を狙う浪人や鉄火肌の娘とともに宿場町の悪人一味を一掃する。かつて、老中松平和泉守の隠し目付だったあざみ鬼十郎は、なぜか和泉守を裏切り素浪人となった。以来、鬼十郎は和泉守の命を受けた部下たちや一攫千金を目論む賞金稼ぎに命を狙われる身となる。日光街道を旅する今も、鬼十郎は大八・丹膳の二人組に付きまとわれていた。そこでやくざに絡まれていた鉄火肌の女・お紋に頼まれて鬼十郎たちは赤目宿に向かう。