There is a sort of perverse existentialism at play in Yojimbo. A lone ronin (masterless samurai) walks into a small town. The buildings are just barely hanging together and the streets are dusty. If the place reminds viewers of the hardscrabble hamlets of the Old West, that's because American westerns, especially those of John Ford, were a powerful influence on director Akira Kurosawa's approach and visuals. The samurai, who, after looking out a window at a field of mulberries, will tell someone his name is Kuwabatake Sanjuro ("Mulberry Field thirty-year-old"), learns that the town is ruled by two criminal families. They are equally matched in strength and fighting ability—not to mention brutality, arrogance and stupidity—so their constant skirmishing prevents any kind of real progress, but keeps the coffin maker busy.
It's not hard to tell what kind of a place this is. One of the first things Sanjuro and we see is a dog running down the street with a human hand in is mouth.
Sanjuro realizes that he can rent himself out as a bodyguard (yojimbo), first to one family and then to the other, playing both sides against the middle until the two families wipe each other out. At first glance we may think he is doing this to free the town of its merciless bosses, but it quickly becomes apparent that his real goal is his own amusement. There is a tall guard tower in the center of town, with a warning bell at the top, and Sanjuro likes to climb to the top so his view of the stabbings and fist fights will be unimpeded. Like any good existentialist, he knows that any meaning he can find in life is merely in the living—but the only meaning that means anything to him is the macabre pleasure of siccing two rabid dogs on each other. As Popeye's pal J. Wellington Wimpy used to say, "Let's you and him fight."
He does perform on good, altruistic deed. A farmer and his wife have been separated by one of the clans and the wife turned into a pleasure girl for one of the sparing punks. The farmer and his son (maybe four or five years old) can only watch this happen for fear of death. Despite an apparent lack of affection or respect for this couple, and an equal disgust at the blubbering of the traumatized child, Sanjuro kills six men who have been guarding the woman, thereby allowing her to reunite and skip town with her family. When the villains discover what they consider to be his treachery, he is beaten almost to death.
When Sanjuro causes trouble resulting in people killing each other—and most of these minions seem far more stupid than evil—all goes well with him and he enjoys himself immensely. When he does a good deed, he gets the crap beaten out of him. As they say, no good deed goes unpunished.
Toshiro Mifune is Sanjuro, and he delivers the most natural performance in the film. Everyone else exists in the realm of caricature, but that may be due to conventions of Japanese comedy—it could even be a sly parody of John Ford's penchant for broad comic interludes in his westerns.
Yojimbo is Kurosawa's most popular movie in Japan. He and Mifune followed it up with a sequel, Sanjuro, which is even more a recognizable comedy. And I would be remiss if I didn't point out that Yojimbo was unofficially remade by Sergio Leone as A Fistful of Dollars. Leone's film looks like a blatant steal, but Kurosawa admitted that he had taken the plot from Dashiell Hammett's Continental Op detective novel Red Harvest. There is nothing new under the sun, whether it's a Son of Italy or the Rising Sun.