Sanjuro (Mifune) runs rings around nine naïve and clean-cut samurai and two genteel ladies while cleaning up a spot of corruption in local government. Kurosawa plays most of it for laughs by expertly parodying the conventions of Japanese period action movies. Most of the action is relatively bloodless, but in the very last scene he stages a startling switch of mood with an intense finale which may well be the briefest, and most breathtaking, duel in all cinema.

Yojimbo introduced the character calling himself 'Sanjuro' (which means 'thirty years old'), the scruffy, mercenary, cynical ronin (masterless samurai). The public had taken this maverick figure to their hearts and demanded a sequel. Strictly speaking, Sanjuro (Tsubaki Sanjuro) is not a 'sequel' to the earlier film, since it seems to take place at a slightly earlier period of Japanese history. Yojimbo is very exactly placed in the 1860s, the final years of the Tokugawa era. The period of Sanjuro is not specified, but it appears to be set during a more socially stable period, maybe a decade or two earlier.

Much of the humour derives from the contrast between Sanjuro's practical, down-to-earth behaviour and the naivety of the young samurai to whom, rather reluctantly, he becomes the guardian and mentor - a humorous treatment of the master-pupil theme that so often recurs in Kurosawa's films.

Despite its tongue-in-cheek humour, Sanjuro is made with all the fluid elegance of Kurosawa at the height of his powers. Even at his most playful, Kurosawa has serious points to make about Japanese society and its overwhelming urge towards social conformity.