From The Emperor and the Wolf by Stuart Galbraith IV (New York: Faber and Faber, 2001):

[Toshirô] Mifune's next film would be the picture that deeply etched his screen persona, to both good and bad effect, for the rest of his life. In Yojimbo ("Bodyguard"), Kurosawa toys with the chambara genre, amusedly turning it inside out, much like Mifune's self-satisfied title character. Kurosawa had subverted the genre's conventions before, in Rashomon, Seven Samurai, and The Hidden Fortress, although playing with the genre had been a secondary concern. By contrast, Yojimbo, a black comedy, is a direct response to the mindless chambara Toei, Daiei, and Nikkatsu were churning out with great success and reckless abandon.

Kurosawa's revolutionary approach extended to the film's swordplay choreography, music, and sound effects.

[In chambara films], you used to hear only the sound of the sword or the samurai's yell [explained script supervisor Teruyo Nogami]. But our director, Kurosawa, asked the experienced sound mixer Ichiro Minawa, "Don't you think there would be some kind of sound when somebody is cut with a sword?" I heard they discussed this while standing in front of the Toro commissary. It was hard to find anyone willing to participate in this experiment. Anyway, Mr. Minawa thought about it, and made more than ten sound effects. I remember him hitting and stabbing cuts of pork and beef that he bought from a butcher. He said it was expensive buying big cuts of meat. And so, the meat he attacked became food for the crew. According to Mr. Minawa, beef and pork were too soft to make a sound. He needed something bony. Finally he put some chopsticks in a whole chicken and then attacked it with a sword . . . On TV or in movies, they always use this kind of sound effect now, but Yojimbo was the first.

The new sound effects were combined with graphic makeup. When the yojimbo cuts down one of the thugs, blood spurts onto the wall behind him. When Sanjuro kills Unosuke (Tatsuya Nakadai), the yojimbo's pistol-carrying archrival, a puddle of blood spreads beneath him. This level of graphic realism, particularly in contrast with its comic elements, was unprecedented in Japan or anywhere else, and years before Bonnie and Clyde (1967) and The Wild Bunch (1969) shocked American audiences.

The wall-to-wall music was also unlike anything heard in a chambara film before. With Yojimbo, Masaru Sato established himself as one of Japan's top film composers. "Up to that point chambara films had a very particular style of music [i.e., faux-traditional, mainly incorporating Japanese instruments]. It was total nonsense to my ears. It had no sense of universality. Mr. Kurosawa said, 'Write whatever you like, but please don't write chambara music!' So I started from scratch, with elements from Westerns mixed with traditional Japanese instruments. I tried to reflect the barbarism of the period. Since then, chambara music has changed quite a bit."

Yojimbo redefined Mifune's screen persona. Up to now his samurai roles outside of Kurosawa's films were more along the lines of Musashi Miyamoto. Seven Samurai's Kikuchiyo was grounded in reality. In Yojimbo, Kurosawa and Mifune created a myth, one no less significant than that of Shane or Ethan Edwards or the Wild Bunch.

"Shrugging and scratching myself were my own ideas," Mifune told the Film Daily's George E. Eagle. "I used these mannerisms to express the unemployed samurai, penniless, wearing dirty [kimono]. Sometimes this kind of man felt lonely, and these mannerisms characterize the loneliness."

[Kazuo] Miyagawa, being Daiei's top cinematographer, hadn't worked with Kurosawa since Rashomon eleven years earlier, but they resumed their symbiotic relationship without missing a beat—Miyagawa likened it to a wife returning to her old husband. "We used three cameras," Miyagawa recalled, "but we used them simultaneously only for the teashop scene. We used two cameras for about a third of the picture, and one camera for another third. Some of the younger crews use multiple cameras to save time, but Mr. Kurosawa uses them so he won't have to interrupt an actor's performance."

In later years, [Sergio] Leone would downplay Yojimbo's influence. But as biographer Christopher Frayling makes clear in Sergio Leone—Something To Do With Death, Leone directly used Kurosawa's film as the model for A Fistful of Dollars.

According to Frayling, Leone had seen Yojimbo in late 1963, approximately one month prior to completing his first draft of Dollars. Leone's wife, Carla, recalled, "I remember going to see Yojimbo with him, and he got the idea of turning it into a Western there and then. Director Sergio Corbucci recalled Leone "slaving over a moviola machine and copying Yojimbo, changing only the setting and details of the dialogue." And during the Dollars production, word came down from Jolly Film (one of the production companies bankrolling the picture) to "refrain under any circumstances from mentioning the word Yojimbo." Leone himself pleaded ignorance, saying that he had always been prepared to acknowledge Yojimbo and that there was simply some mixup regarding the payment of royalties. He may have been oblivious to the legal hurricane he was creating, but the money men clearly were not.

For his part, Kurosawa liked Leone's film, but, in a letter to Leone, was firm in his assertion that he be financially compensated. [Postproduction head Tonino] Valerii explained, "It was addressed to Sergio and it said, 'Signor Leone—I have just had the chance to see your film. It is a very fine film, but it is my film. Since Japan is a signatory of the Berne Convention on international copyright, you must pay me.' Now Sergio was so naïve that he waved this letter around to everyone. The letter was really offensive, with its accusation of plagiarism, of copying Kurosawa's film, but he didn't seem to realize it. He couldn't get beyond the fact that Kurosawa had written him, and called his work a very fine film. He was so thrilled about this. When anyone tried to get him to put the letter away, he kept asking, 'Why?'"

Finally, a year after its Italian premiere, an out-of-court settlement was reached whereby Kurosawa would receive 15 percent of Fistful's worldwide receipts, with a guarantee of around $100,000. A subsequent lawsuit was filed by Toho and Kurosawa regarding the picture's American release. Jolly Film and UNIDIS, the co-producer and Italian distributor of the film, filed their own suit against Leone and Eastwood over the sequel, For a Few Dollars More, which was produced without their participation. All this further delayed United Artists' release of A Fistful of Dollars in American until 1967. When the film was finally shown in the United States, no screenplay credit was given at all.