Criterion is about to release glistening new transfers of two catalog staples, Akira Kurosawa’s “Yojimbo” (1961) and its sequel, “Sanjuro” (1962), suitably boxed together. Like the first two “Godfather” films, they enlarge each other. “Yojimbo” (bodyguard) was Kurosawa’s international blockbuster, and the character of Sanjuro (the bodyguard’s alias), an ultimately infallible freelance samurai, endures as Toshiro Mifune’s most popular role. Indeed, if neither film is ranked with Kurosawa’s masterworks, it may be because they so successfully turn the screws of boys’ life adventures — violence, revenge, comedy, suspense. Seek elsewhere for sex and romance. It is no more possible to imagine Sanjuro in an erotic clinch than on a horse with a pistol.

Oh wait. That’s precisely how Sergio Leone envisioned Sanjuro when he remade “Yojimbo” as “A Fistful of Dollars” (1964), though he, too, dispensed with amours. Yet for all of Leone’s fidelity to Kurosawa and for all of Clint Eastwood’s subsequent chin scratching in the Mifune manner, the Japanese films remain essentially untouchable as character studies. Sanjuro may work as more of a fantasy figure than the monarch in Kurosawa’s “Ran,” the clerk in “Ikiru,” the manufacturer in “High and Low,” or the doctor in “Red Beard,” but he is no less a being of universal application. “Yojimbo” holds up a mirror to the West, showing a Japanese reflection of our most familiar wish-fulfillment hero: the tough, unsentimental, yet good-hearted guy who wanders into a strange town and cleans it up by killing most of the residents. Kurosawa employed impeccable, if unacknowledged, source material.

Dashiell Hammett’s first novel, 1929’s “Red Harvest” has a shadowy movie history. A milestone in crime fiction, it thumbs its nose at the legions that attempt to adapt it: Despite countless treatments, it has never been filmed. Upon its publication, Paramount bought it for producer Walter Wanger, who, had he trusted the book, might have got the jump on 1931’s “Little Caesar” and the Warners gangster cycle. Instead, he replaced Hammett’s operative with a dopey newspaperman and framed the plot as a vehicle for singer Helen Morgan. The result, 1930’s “Roadhouse Nights,” is now valued only for preserving the legendary nightclub act of Clayton, Jackson, and Durante — it was Jimmy Durante’s first talkie.

“Red Harvest” may be too novelistic to suit the movies: If the laughably high body count is cinematically apt, the profusion of characters, gin-soaked dialogue, and sequential mysteries are more of a challenge. Yet it introduced or at least popularized three concepts that movies have gnawed on for decades, without attribution.

The first is the detective as avenging angel, often transposed to the West — in “Shane,” “Bad Day at Black Rock,” “High Plains Drifter,” the television series “Have Gun, Will Travel” and its urban remake, “The Equalizer,” and many others.

The second is the link between business and crime: The town’s thugs are brought to power when legitimate capitalist interests are corrupted by greed — an abiding Marxist critique so commonplace that it is hardly noticed in films as diverse as “Mr. Smith Goes to Washington,” “The Roaring Twenties,” “This Gun for Hire,” “Force of Evil,” “On the Waterfront,” or “The Godfather.”

The signal concept, however, is the one that guns the plot: The stranger pretends to hire out to all sides, manipulating them into mutual self-destruction. This device, coupled with one or both of the others, marks a film as a “Red Harvest” baby, a category brought to fruition in “Yojimbo” and then diminished by various degrees in such variations as “A Fistful of Dollars,” “Miller’s Crossing,” and “Last Man Standing.” Kurosawa, who sued Leone for stealing his film (“A Fistful of Dollars” was released in America with no writing credits), not only denied a Hammett connection but expressed surprise that no one before him had thought to exploit a rivalry between two “equally bad” sides. Actually, Homer had hit that one out of the park.

Kurosawa borrowed more than just concepts. The scene in “Yojimbo” in which one gang blows up a rival’s stronghold and butchers the unarmed leaders is taken straight from “Red Harvest.” More to the point, the character of Sanjuro has several points in common with Hammett’s detective. He won’t work without a client and advance payment; his morality is far from mercenary and he takes orders from no one (least of all clients); he is physically vulnerable, and he has no name. The Op takes a new alias every time he checks into a hotel.

Still, “Yojimbo” is quintessential Kurosawa, and an inspired example of solving the problems of adaptation. Unlike the American avenger, who sets out on a mission or is summoned, Sanjuro relies on chance. He throws a branch in the air and follows its direction. Having taken that road, he immediately overhears a family arguing about war, honor, and work — the film’s one acknowledgement of the farmers striving to make do beyond the snake pit of a town. The image of the wife, working heedlessly at a loom, stands in marked contrast to everyone else in the film.

When Sanjuro arrives on the main street, he stops at a restaurant, where the proprietor, pointing through window slats, identifies the characters and sets up the plot. The rest is Sanjuro’s chess game. Hammett’s Op had to contend with four warring factions plus the industrialist behind them; Kurosawa sensibly reduces the parties to two, each with a businessman trying fecklessly to pull their strings and ending up either mad or dead. In the end, Sanjuro steps over the bodies, waves to the few survivors, and leaves.

A year later, by popular demand, Sanjuro returned in the eponymous sequel, this time as a wilier observer who sees through the fakery of his opponents and accepts, with payment, the responsibility of mother hen for a group of credulous young noblemen all too eager to walk into a trap. “Sanjuro” is a funnier film, and the mode is intimate rather than epic. The powerful officials are as corrupt and desiccated as ever, but the supporting cast includes a traitor who sides with the good guys after a hot meal, and two ladies who are not going to let a massacre or two disrupt their tempo and repose. Kurosawa offers two of his finest conceits: the river of camellias to signal attack and the unforgettable climactic onestoke duel, which produces an arterial gush that corrupted any number of filmmakers who prefer gush to character.

An interesting question posed by the diptych is: Which story comes first — does “Sanjuro” follow the events of “Yojimbo” or precede them? The point is intriguing because the themes of the films are contradicted by their style. In “Sanjuro,” the samurai learns that the best sword stays sheathed, and appears to have attained a wisdom far removed from the bloodletting of “Yojimbo,” suggesting a chronological followup. Yet the comic, bourgeoisie chamber-like style of “Sanjuro” feels like a precursor to the stylish grandeur of “Yojimbo,” where the hero undergoes a resurrection and satisfying triumph.

Conversely, if “Sanjuro” has the look of a trial run before the stateliness of “Yojimbo,” then we must assume that the notion of resisting violence has itself been resisted — that Sanjuro’s renunciation merely reflects his foul mood after an unpleasant killing.

The new prints are so good that the earlier ones now seem subpar for Criterion. The aspect ratio has been corrected and the imposed English titles and preface removed. The contrasts are more vividly defined and the translation is presumably more accurate and certainly wittier, with the addition of lines like, “I’ll make sashimi of them”; the question, “So that’s Tazaemon, the drummer?” now reads, “Hey, is that your nitwit mayor?” and a yelped “Mother!” is suitably changed to “Mommy!” The sound does justice to Masaru Sato’s magnificent Japanese-percussion-meets-avant-garde-jazz score. Extras include commentaries, trailers, and from the series “Akira Kurosawa: It Is Wonderful To Create.” Now if Criterion will only upgrade “High and Low.”

Mr. Giddins’s most recent book, “Natural Selection: Gary Giddins on Comedy, Film, Music, and Books,” is available from Oxford University Press.