It tells the story of the rōnin Hanshirō Tsugumo,[3] who requests to commit seppuku (harakiri) within the manor of a local feudal lord, using the opportunity to explain the events that drove him to ask for death before an audience of samurai.

A rōnin called Tsugumo Hanshirō arrives at the estate of the Iyi clan and says that he wishes to commit seppuku within the courtyard of the palace.

Saitō scornfully recalls the practice of rōnin requesting the chance to commit seppuku on the clan's land, but in fact hoping to be turned away and given alms.

Infuriated by the rising number of "suicide bluffs", the three most senior samurai of the clan—Yazaki Hayato, Kawabe Umenosuke, and Omodaka Hikokuro—persuaded Saitō to force Motome to follow through and kill himself, ignoring his request for a couple of days delay.

Enraged that any samurai would "pawn his soul", the House of Iyi forced Motome to disembowel himself with his own bamboo blade, making his death slow, agonizingly painful, and deeply humiliating.

To the shock of Saitō and the Iyi retainers, Hanshirō successively names Hayato, Umenosuke, and Hikokuro — the three samurai who coerced the suicide of Motome.

After provoking Saitō's laughter by calling the samurai moral code bushido a facade, Hanshirō reveals the last part of his story.

In a fierce battle, Hanshirō kills four samurai, wounds eight, and contemptuously smashes into pieces the antique suit of armor which symbolizes the glorious history of the House of Iyi.

Terrified that the Iyi clan will be abolished if word gets out that "a half starved rōnin" killed so many of their retainers, Saitō announces that all deaths caused by Hanshirō shall be explained by "illness".

The notions of honor and bravery associated with it can be a false front, as the protagonist puts it, serving more as a means of preserving reputations than of actually atoning for a crime or misdeed.

[1] In a contemporary review, the Monthly Film Bulletin stated that Masaki Kobayashi's "slow, measured cadence perfectly matches his subject" and that the "story itself is beautifully constructed".

The review praised Tatsuya Nakadai's "brilliant, Mifune-like performance" and noted that the film was "on occasion brutal, particularly in the young samurai's terrible agony with his bamboo sword" and that although "some critics have remarked [...] that being gory is not the best way to deplore wanton bloodshed, Harakiri still looks splendid with its measured tracking shots, its slow zooms, its reflective overhead shots of the courtyard, and its frequent poised immobility".

[9] The New York Times reviewer Bosley Crowther was unimpressed with "the tortured human drama in this film" but added that "Mr. Kobayashi does superb things with architectural compositions, moving forms and occasionally turbulent gyrations of struggling figures in the CinemaScope-size screen.

[11] Donald Richie called it the director's "single finest picture" and quoted Kobayashi's mentor Keisuke Kinoshita who named it among the top five greatest Japanese films of all time.

[12] Audie Bock wrote: "Harakiri avoids the sentimentality of some of his earlier films, such as The Human Condition, through a new emphasis on visual-auditory aesthetics with the cold formality of compositions and Takemitsu's electronic score.

[13] Roger Ebert included Harakiri in his list of "Great Movies", writing in his 2012 review: "Samurai films, like westerns, need not be familiar genre stories.

By playing strictly within the rules of Bushido Code which governs the conduct of all samurai, he lures the powerful leader into a situation where sheer naked logic leaves him humiliated before his retainers".