Sword of Doom is a jidaigeki film released in 1966. It was directed by Kihachi Okamoto and stars Tatsuya Nakadai. It was based on the serial novel of the same title by Kaizan Nakazato.Check it out [here].
When the wife of the Shogun's Decapitator is murdered and he is ordered to commit suicide by the paranoid Shogun, he and his four-year-old son escape and become assassins for hire, embarking on a journey of blood and violent death.
Hanzo Itami is an incorruptible Edo officer who learns that an infamous killer has fled from his island prison. Hanzo begins tracking him down using his unorthodox interrogation techniques.
In 1701, Lord Takuminokami Asano has a feud with Lord Kira and he tries to kill Kira in the corridors of the Shogun's palace. The Shogun sentences Lord Asano to commit suppuku and deprives the palace and lands from his clan, but does not punish Lod Kira. Lord Asano's vassals leave the land and his samurais become ronin and want to seek revenge against the dishonor of their Lord. But their leader Kuranosuke Oishi asks the Shogun to restore the Asano clan with his brother Daigaku Asano. One year later, the Shogun refuses his request and Oishi and forty-six ronin revenge their Lord.