Three men sentenced to death are spared and changed into “shadows executioners”, a group of ruthless ninja working for mysterious high ranking officials. During their investigation on some illegal business, one of them, called “Yazuke the Viper”, finds his abandoned daughter, Ocho, who has now become a mistress of Denzo, a smuggler. After Yazuke’s death, Ocho is also recruited as a “shadows executioner”, with the task of completing her father’s mission.
Samonji, a reporter, receives a message on his answering machine from his friend Takada that says "stop it... zero plan! February." Learning that Takada is dead, Samonji begins an investigation. He and his younger sister Fumiko investigate major events happening in February but cannot find anything relevant. Meanwhile, Kanzaki, a doctor who works at a clinic on a remote island, is working on a plan to extort two billion yen.
Follows the fluctuating fortunes of three ronin in feudal Japan who wander from castle to castle, selling their services to whichever lord will fill their rice bowls. Though they use the servants' entrance, they still feel themselves bound by the samurai code of Bushido; and this tension leads to tragedy.
