Shinobi no mono: Zoku Kirigakure Saizô (1964)

In part five of the 8-part Shinobi No Mono Ninja film series the heroic ninja Kirigakure Saizo (Raizo Ichikawa, of Sleepy Eyes of Death fame) serves the daimyo Sanada, played by Lone Wolf and Cub star Tomisaburo Wakiyama. They are assaulted by Ieyasu and his soldiers. They flee to an allied camp, and once there start plotting how to fight back and win the war.

They come across a gun merchant with a unique, three-barrel gun, giving the holder incredible fire power. They begin to strategize ways to find out how the merchant selling these firearms has acquired them, hoping that possession of these weapons in their arsenal will lead to ultimate victory. The merchants of Tanegashima are the makers of the gun, and claim they have made it according to a blueprint gained from the only Western traders they are allowed to do business with, the Portuguese. The Sanada partisans know that can't be true because the 3-barrel gun is made of iron too fine for the Portuguese to have access to. They must unravel the secret of the "3-barrel gun". Kirigakure is sent to the Island city of Tanegishima to solve the mystery. Once there he will need all his ninja skills to survive, not only the Tanegishima cartel and their Chinese allies, but enemies from his past, in the form of the daughters of a slain enemy ninja. Can he get the job done and stay alive?