藤沢周平の用心棒日月抄

13th year of the Genroku era. Matahachiro Aoe, a samurai of the Shonai clan from Dewa Province, accidentally learned that a group of conspirators led by the main vassal of Tango Otomi were planning to poison the Lord. Matahachiro decided to consult with the father of his fiancée Yuki, Kizaemon Hiranuma, an employee of the security department, and told him everything. However, when Matahachiro was about to leave for home, Hiranuma attacked him from behind and Matahachiro defended himself by killing his future father-in-law in front of Yuki. Matahachiro escapes to Edo and provides bodyguard services to earn a living. He is pursued by assassins who are sent by conspirators from his former clan. And soon he also becomes involved in the conflict between Asano and Kira, which arose due to a blade wound in a pine corridor in Edo Castle...