Watanabe Kazuma's younger brother is brutally murdered by Kawai Matagoro. However, Kazuma's vendetta is denied since the Japanese law in the 17th Century only allowed a samurai to avenge his father or older brother, but not a younger brother. This incident makes his family member Araki Mataemon face his best friend in order to clear path for Kazuma. The tension mounts as they must carry out the vengeance before the murderer Kawai Matagoro reaches the safety of a direct retainer of the Shogun.