Eleven Samurai aka Ju-ichinin no samurai

In the 1830's, the Shogunate had become sclerotic and kleptocratic (or more so than usual). The youngest brother of the current Shogun is the epitome of the spoiled brat, believing that since he is Tokugawa, he can do anything. Crossing into another territory during a hunt, he kills the daimyo who confronts him. When this is reported to the Shogun's council, they decide that, since no one in the Shogun's family can be in the wrong, the other clan must be punished for trying to bring the Tokugawa into disrepute. Given a month before their dissolution, the clan sets up an assassination squad to avenge their lord's death and the clan's honor.