This was the original Thirteen Assassins movie, that that 2010 one was based on. The movie begins in the first year of the Koka period, October 16th, 1844. In front of the gate at the home of Elder Doi, Mamiya Zusho, Chief Retainer of Edo, committed sepuku. He was a vassal of Lord Natisugu who was the Shogun's younger half-brother. The Shogun's cabinet discusses Lord Natisugu's deficiencies. The Shogun has told the cabinet to handle the matter discretely.
Shimada Shinzaemon, who is an inspector for the Shogun is summoned. Lord Doi has chosen Shinza for a task. Lord Doi tells Shinza that Lord Natisugu is to be made a member of the Council of Elders, and that can not happen. Lord Doi has Shinza listen to Makin Yukie tell how the previous year Lord Natisugu stopped at Makin's house. Makin tells how his son Uneme and daughter-in-law Chise had been married two months. Lord Natisugu raped Chise and then killed her husband. Chise then killed herself.
Lord Dao tells Shinza because he is a representative of the Shogun he can't get involved in what must be done. "But if it issn't done, order will turn into chaos, and calamity will infect the entire nation." Shinza says: "It is a good cause for a samurai to die for." "I will accomplish it spendidly. You will see."
Sir Hanbei, of the Akashi clan, is not happy that Mamiya's relatives have been arrested but it was ordered by Lord Natisugu. Hanbei tells Lord Natisugu that Lord Dao has requested compassion for Mamiya's relatives. Lord Natisugu responds by putting them all to the sword. Hanbei orders no one to speak of what happened.
Hanbei knows Lord Dao must do something and orders a vassal to get the name of all of his visitors. Hanbei finds out that Makino Yukie met with Inspector Shimada Shizaemon. Hanbei knows of Shimada's talent with a sword. He says that unlike him, Shimada is from a famed hereditary vassalage.
A ronin, Hirayama, who is a disciple of Shimada comes to offer his support. One of Shimada's advisors, Inspector Kuranaga had selected five men from the ranks who he felt could help. Shimada tells them of the plan to take Lord Natisugu's life. Lord Natisugu has over 5000 samurai in the Akashi fief. He has another 1500 in Edo. They must attack when he is travelling.
The group picks up two more men. One a disciple of Hirayama and the other a ronin who wants 200 ryo for his services.
Lord Natisugu's men begin preparation for his trip from Edo back to Akashi. Hanbei knows Shinza is lying in wait. Then Hanbei stops in to see Shimada. Hanbei tells Shimada that he has always been a role model. He has climbed through the ranks, but now he is paying for that climb. They both promise to act like samurai no matter what happens.
Shimada and his men plan as to where the ambush should take place. They first try at the river but Hanbei is ready and has two palanquins, with on being a decoy. He also has samurai for all footmen and attendants. So there are over 100 samurai. Shimada doesn't know which one to attack. Hanbei has won round one.
A final plan is devised for the twelve. They plan to get Sir Makino Yukie to bar Lord Natisugu from entering the Owari province. They will then be able to ambush him at Ochiai. another town that he will have to travel through.
When Hanbei and Lord Natisugu get to the owari province there is a sign up on the bridge saying they are barred from entering Owari land. When Lord Natisugu tries to cross Makino Yukie tells him who he is. Lord Natisugu then gets muskets pointed at him.
Lord Natisugu decides not to take a safe route. He does not want to become a laughing stock. His route will take him through Ochiai, just as Shimada planned. The 12 samurai begin to turn the town in to a killing ground. But then a problem turns up. A "country samurai" from the town learns of their plans and wants to join up. He wants to fight so the headman of the town, who ignores him, might consider him for his daughter who he loves. And then they were thirteen.
Lord Natisugu's group vanishes for a while and the thirteen wonder if they are coming, but then the sentry comes with the news that they are coming. 53 men in all, all on horseback. They enter the town and they come to a wall. When they try to retreat the bridge falls in behind them. Then the arrows start to fly. a great many men fall and then the swords come out. The killing continues and slowly the members of the thirteen begin to fall.
Finally Shimada gets Lord Natisugu alone. Lord Natisugu tries to run and screams for Hanbei but Shimada chops him down. Shimada and Hanbei then duel and Shimada lets Hanbei kill him. Hanbei is then killed by oone of the thirteen. Shimada says: "I had to kill your Lord. It was my duty as a samurai. And it was your duty as a samurai to kill me, wasn't it?" Hanbei says: "I..I understand. Well done, Shinza."
A very good samurai movie.