Three men sentenced to death are spared and changed into âshadows executionersâ, a group of ruthless ninja working for mysterious high ranking officials. During their investigation on some illegal business, one of them, called âYazuke the Viperâ, finds his abandoned daughter, Ocho, who has now become a mistress of Denzo, a smuggler. After Yazukeâs death, Ocho is also recruited as a âshadows executionerâ, with the task of completing her fatherâs mission.