Akira Kurosawa told Toshirô Mifune that his character was like a wolf or a dog and told Tatsuya Nakadai that his character was like a snake. Inspired by this direction, Mifune came up with Sanjuro's trademark shoulder twitch, similar to the way a dog or wolf tries to get off fleas.
Sergio Leone was inspired by this film and made the famous "spaghetti western" A Fistful of Dollars (1964) with a similar plot. However, because Leone did not officially get permission to remake this film, which was copyrighted, Akira Kurosawa sued him and delayed the release for three years. Leone paid him a sum plus 15% of the profits. Interestingly enough, Kurosawa himself stated that he based his movie on The Glass Key (1942), an adaptation of Dashiell Hammett's novel, without officially crediting either source. However, various critics and readers of Hammett's work have noted that Yojimbo's overall plot is closer to Hammett's "Red Harvest" and not "The Glass Key."
Yojimbo means bodyguard in Japanese. In context it can also be translated as protector or escort.
Yojimbo was an obvious inspiration for Sergio Leone's classic A Fistful of Dollars (1964) although it was not credited as the source material for the film. Walter Hill, however, also remade Yojimbo years later as Last Man Standing (1996) starring Bruce Willis, and credited Kurosawa's film as the original source. All three films follow a similar plot, although each takes place in a far different setting and time in human history.
This was a deliberate attempt by Akira Kurosawa to revise the cinema's attitude towards onscreen violence. He wanted to show the damaging effect of violence, rather than the slightly anodyne way that it usually had been depicted before. (He would later come to regret this move, as it spawned a mass movement in international cinema that hasn't abated even today.)
Akira Kurosawa: [weather] Like in most Kurosawa films, rainy weather is present in a few scenes, increasing the effect of the characters' discomfort. The windy weather all throughout the film represents the chaotic life in the town.