Unless you really know your Japanese cinema, there's a good chance you'll have never heard of Hanzo the Razor, the lead character of three films from 1972 to 1974, all starring and co-produced by Katsu Shintaro. They were certainly new to me. Made during a period of changing public tastes, they present something of a dilemma for a modern audience. Stylish and highly engaging, they are also very much products of their place and time, and include an element that... well, let me tell you a little about the character and setup and you'll soon understand.

Itami Hanzo is a law officer in Edo period Japan. At the start of the first film he refuses to sign a blood oath required of all policeman because, he tells his superiors to their faces, the force is riddled with corruption. He will do his job and do it well, but he will do so without lending his approval to the bribe-taking on which the department appears to thrive. This enrages his immediate boss, Onishi Magobei, but Hanzo's not too impressed with him either and there's not much Onishi is ready to do about it. After all, Hanzo is not just a good cop, he's the best the department's got.

OK, so far so good. Despite being set in Edo Japan, this is familiar existentialist cop stuff, Dirty Harry for the samurai age if you will. Well, not quite. Once he's back at home we find Hanzo kneeling on a painful looking base of triangular wooden blocks as his two servants pile stone stabs onto his legs, crushing his limbs and drawing blood. They protest at being ordered to hurt him so, but he saved both of them from jail and they are thus in everlasting obedience to their master. This is not some masochistic or religious self-punishment, but an attempt by Hanzo to get inside the criminal mind, to understand the pain of the torture some have suffered before turning to a life of crime. His body shows the scars of previous violence he has endured in the name of such enlightenment. Hanzo is a man whose dedication to his job borders on the obsessive, some might say the psychotic.

But this is nothing. Hanzo has another daily exercise, and this is definitely one you won't have seen Dirty Harry indulging in. Are you ready for this? After a long soak in a hot bath, he washes his penis with steaming hot water, places it on a wooden block prepared especially for the purpose and repeatedly beats it with a large stick. He's been doing this so long that the wood now bears the imprint of his erect member, which he then inserts into a casket of rice and effectively has sex with it. As a result he has a permanent and sizeable hard-on.

Still with me? Well try this for size. Hanzo is, as you'd expect, a skilled fighter who always gets his man, one who will smash in the nose of a suspect and proclaim him dead in order to haul him off and continue his cross-examination in private. For women, though, he has a very particular method of interrogation, and this is where the difficulties will set in for a modern and hopefully enlightened western audience. To secure the co-operation of his female prisoners, Hanzo puts his carefully prepared and oversized penis to use and rapes them. His favourite method, which he describes as his 'special torture', involves them being hauled aloft in a large net and lowered by his servants onto his member, lifted repeatedly up and down and then spun round in a circle. And they tell him what he wants to know not because of the pain or the indignity or the horror of what is happening, but because they don't want him to stop.

You see the problem.

Now I'd written all of the above before I read the notes by respected Asian cinema writer Tom Mes, who acknowledges the issue but suggests that if you're in any way outraged by this concept then you probably haven't seen the film, just read a plot summary, and that you can't take it too seriously anyway because it's intended as parody. To a degree he's right. Hanzo's keep-it-hard exercises alone seem to indicate that we're in comic book territory (the series was based on a Manga by Kazuo Koike) and there is a deliberate absurdity to the whole premise that is acknowledged in the handling of these sequences, with one glimpse of Hanzo's todger enough to make any woman go wide-eyed and slack-jawed in disbelief. But Mes is also, like a few other reviewers I've encountered, a little too quick to gloss over what will definitely cause offence to some, even if it is light hearted in tone. The "it's only a movie" response is both common and valid, but every such reaction to Hanzo's activities I've read has been from a male viewer and I'm always curious to know just how confident they'd be defending these scenes to a genuine rape victim.

It's important, of course, to remember just when and where the films were made. Mes draws parallels with 60s western movie icon James Bond, a super-cool secret agent whose sex appeal was such that women would drop their knickers at the raise of an eyebrow. Hanzo also shares a few traits with early Clint Eastwood characters (whose Man With No Name was itself drawn from the Japanese jidaigeki genre), not least the anti-hero at the centre of High Plains Drifter (1973), whose first act on riding into the frontier town of Lago is to drag a mouthy woman into a barn and rape her, a scene made all the more uncomfortable today by the pacifying effect it ultimately has. This is the male avenger at his most primitive – men are shot or stabbed, women are raped, but penetration of some sort key to the punishment of both.

More significant is the cultural element. This is Japanese cinema from the early 1970s, when the straight jidaigeki (historical) and specifically chambara (swordplay) films were fading in popularity and pinku eiga (pink films, a uniquely Japanese form of softcore porn) were on the rise. Japanese society is a historically patriarchal one and sex and violence would happily go hand-in-hand in art and entertainment, to a degree that can seem alarming to a modern western audience. Hentai manga in particular has its darker corners, not least Keiko Aisaki's Rapeman, a short-lived comic book series from the late 1980s that delivered on its title and gave birth to seven live action features and a full length anime, none of which have – surprise surprise – turned up on UK DVD. It's a sign of the changing face of Japanese cinema that in Miike Takashi's 1995 Shinjuku Triad Society, rape is still employed as a tool of torture and punishment, but it's the men who can expect to be on the receiving end.

But if you can tolerate or perhaps turns a blind eye to Hanzo's razor and the use to which it is put, this is a trilogy most definitely worthy of your attention. These are jidaigeki films invigorated by energetic fight choreography and Katsu's practiced sword hand, and are infused with a late 60s distrust of the establishment. In Hanzo's world, just about everyone in a position of power is corrupt to the core – even his own boss, Magobei Onishi, has picked up the nickname 'snake' for his slippery dealings. The only trustworthy recurring characters are Hanzo's servants, colourfully named Devil Fire and Viper, whose reluctant obedience is ensured by irregular reminders of their criminal past and where they'd be if not in Hazo's protective employ – by the second film they only have to hear the words "Show me your arms!", limbs which bear the tattoos of their former criminal status, to groan and capitulate. There's even a perverse element of class war at work – Hanzo readily works his 'special torture' on the wives and mistresses of samurai or high officials, but is willing to defend to the death the honour of a servant girl kidnapped and threatened with gang rape.

The parallels with James Bond extend to Hanzo's impressive armoury and gadgetry, his house a collection of concealed weapons and booby-traps for the unwary. Think you can take Hanzo because he's naked in a hot tub? Think again, as one tap on the wall will place a range of deadly implements within arm's reach. Fancy your chances because you've got him trapped in a narrow corridor? Better watch your step, as that floor might just open and plunge you onto lethal pin cushion of spears. And if you think you can best him in a sword fight then watch out – Hanzo's weapon of choice is a pair of daggers linked by a chain that can block and even incapacitate swords and their users, a device that would usually be more at home in Chinese martial arts movies than Japanese jidaigeki.

Actor Katsu Shintaro made his name as the blind swordsman Zatoichi in a long-running an hugely popular series of films for the Daiei Motion Picture Company, but following Daiei's bankruptcy in 1971, production of the films moved to Toho. By then their popularity and originality was starting to wane – Zatoichi at Large, the first Toho film in the series was the twenty-third overall, and three films later Katsu played Zatoichi for the last time. The actor was clearly keen to establish a new on-screen identity, one with Zatoichi's fighting skills but a little something extra, and no doubt Toho, aware of the changing times and the extraordinary popularity of the pinku eiga films, recognised that this could be potentially lucrative for them. It's not hard to see why the series never made it past three films, though. As Tom Mes notes, Hanzo's method of interrogation and 'special torture' remained undeveloped constants of all three films, and by the third they were already starting to feel like obligatory components.

The sexual politics may be severely dated and even peculiar, but in all other respects the Hanzo the Razor films are a class act. Their blend of old-school swordplay, James Bond gimickery, twisted eroticism and political allegory is as appealing as it is unique, and technically they are sharp as a samurai sword – these are really well made films. It may mean shutting down your sensitivity gland for a few scenes, but for devotees of Japanese jidaigeki cinema, or those with a taste for the unusual or perverse, the Hanzo the Razor films really are a must.

As a final point of interest, I watched all three films with a middle aged female Japanese friend and she enjoyed them a great deal and was not in any way offended or surprised by Hanzo and his singular methods of interrogation. During one such scene involving samurai's wife, I questioned her directly on it. "Doesn't this bother you a bit?" I asked. "What you must remember," she told me as if I'd been there at the time, "is that when this film came out, Japanese audiences liked to see the wife of a samurai being raped. It was a man's dream." This did nothing to dilute my considerable discomfort.

The film that introduced our anti-hero is obviously the one with the most surprises for newcomers, from Hanzo's self-flagellation to his troubling interrogation techniques. I came to this with no knowledge of the content and was left genuinely slack-jawed. My Japanese companion, as I said, was amused but not in any way shocked. Your own reaction will depend on your viewing experience, expectations and personal politics.

In the very first scene, Hanzo is painted as a renegade cop who holds his superiors in contempt, especially when he discovers that one of them – the aforementioned Snake Magobei – is in bed with the same woman as notorious master criminal Killer Kanbei. They don't know the woman's name, but identify her by her lack of pubic hair (don't ask how). Hanzo pays her a visit and spends a long time on the interrogation, and the information he retrieves suggests a bigger plot that may involve corruption at the highest level.

Daffy though some of the film is, the comedy is actually rather stone-faced here, save for a brief interlude involving a group of guards at the North Magistrate's Office played by the Manzai comedy group The Chambara Trio. The drama, though, has enough twists and intrigue and sexually peculiar interludes to launch the series with the right sort of, erm, bang. The western 60s influence is most evident in this film, from the sometimes madly anachronistic soundtrack that could almost have wandered in from a Shaft sequel, to the fight scene shot from unexpected (and not always the clearest) angles.

It's involving and entertaining stuff, a samurai detective story infused with pinku eiga eroticism and a strand of dark humour. The production values are high, the performances enjoyable and the stylish final shot looks forward to the sequels that you'll be glad you have to hand.

The best film in the trilogy starts and concludes on the same bridge, the first encounter reminding us that Hanzo can take on a small army of swordsmen with just his chain-linked daggers and not get a scratch. That the warriors are the personal guard of government treasurer Lord Okubo cuts no ice with this particular law enforcement officer – they're in his way so they have to die. Already dead is Omachi Surugaya, a merchant's daughter and the victim of a botched abortion. I'll leave it to you to guess how that diagnosis is made. This leads Hanzo to a female-run shrine that specialises in such operations, and a convent priestess who sells the virtues of her young female students to the highest bidder from a rabble of well-connected and corrupt noblemen. Plenty for Hanzo to do here, then.

There's more nudity this time and more overt eroticism, not least in the rituals and practices of the exotic abortionist, who turns a medical act into a lesbian come-on and whose self-confident frankness with Hanzo is guaranteed to provide the audience a small frisson of delight. Hanzo gets to hide in the closet of a well-to-do lady whom he then has his way with, and a bald priestess is kidnapped, tied up, tortured and then tortured again in that special way only Hanzo can administer, a sequence that should have the nunsploitation fans hugging themselves with glee.

Viper and Devil Fire are elevated to comedy foils, an energetically hapless double-act that nicely counterbalances Hanzo's unwavering stern and impatient righteousness. Kazuo Miyagawa's cinematography is consistently excellent and the fights are particularly well choreographed to camera, from the close-quarters encounter in Hanzo's booby-trapped house to the climactic battle with Shobei Hamajima and his gang, which builds to a smartly handled stand-off and a satisfying, corruption-busting conclusion. Hanzo even gets a traditional one-on-one final sword fight with a warrior who needs to test his skills against his chosen nemesis and to stride off at the end in brusque, Yojimbo style.

A genuinely compelling and well-made blend of investigative drama, oddball eroticism and jidaigeki action, whose tightly constructed plot, engaging performances and off-the-wall character detail make it the most dramatically and cinematically satisfying of the three films.

The last film in the series kicks off in style with Devil Fire and Viper frightened off from their night-time fishing trip by a ghost (handled in atmospherically kaidan style), something Hanzo quickly exposes as fakery. A quick dip beneath the water uncovers a bamboo pole crammed with gold coins. Hey, we're right next to the shogunate treasury. What d'you think could be going on here?

The third Hanzo story is particularly aware of the comic potential of Hanzo's unique talent and training methods – the image of Devil Fire and Viper nervously relating their supernatural experience to Hanzo as he beats his member with a stick is genuinely funny, topped off by Hanzo's proclamation that he'd rather like to make love to a ghost, just once. He gets his chance, in a way, when he employs his 'special torture' on the ghost's female impostor and she's assassinated just before she talks ("She couldn't have picked a better moment," groans her interrogator).

A deputation of disgruntled shogunate samurai guards pop in for a fight, led by Chozaburo Kato, husband of the unfortunate girl. Inevitably they lose, and Hanzo once again gets political, campaigning for the rights of the underpaid samurai he's just killed and hiding a rebel doctor he has been forced to arrest to allow the man time to build a canon, an instrument that will wake the powerful and corrupt Elder Hotta up to the importance of adopting western technology. Snake Magobei is up to his old tricks, accepting a reward refused by Hanzo and landing himself in Hanzo's pocket as a result. By now Magobei has graduated from frustrated official to excitable clown, something actor Ko Nishimura grabs with both hands and runs with (his frustration at Hanzo's insolence before Elder Hotta is a comical hoot).

The expected elements are all there, but a nice surprise arrives in the shape of Heisuki, an old friend of Hanzo's who is capable of the rare trick of putting a smile on the warrior's face and getting him to relax with a few drinks. He's nonetheless doomed from the moment we meet him – he has a family heirloom, a Nagato Aeo spear, that Hotta covets and expresses his intention to own, and his purpose in the narrative is clearly to die and spur Hanzo into furious action. Hanzo once again has his way with a lady of social standing, but in a scene whose striking cinematography and editing stand it apart from any we've seen before. He even drops in on an orgy, not to participate but to brand the women involved and secure their later cooperation.

It's another full blooded and enjoyable tale with a literally explosive climax and an inevitable one-on-one battle between Hanzo with Heisuki's murderer. The ending leaves the way open for more, but they never appeared. It doesn't really matter – Who's Got the Gold? is a fine film, but the decision to quit at three before the formula began to stale was probably a wise one.

Framed 2.35:1 and anamorphically enhanced, these restored and remastered Toho licensed transfers are simply gorgeous – the colours are rich but not over-saturated, the detail excellent and the contrast and black levels close to perfect. For films first released in the early 1970s, the picture quality here is little short of miraculous.

The original mono soundtrack has been left unmolested and unremixed. Its age is betrayed by a restricted dynamic range and a slight background hiss, but it's otherwise clean of noise and damage and sounds about right for a film of this period.

Although packaged together in a single box set, the individual keep cases are worth a mention for their wonderful covers, which feature unblemished reproductions of the original Japanese posters.

Each disc has the original trailer for the film in question and all are in sparkling shape. There is also a booklet for each film with detailed notes by Tom Mes, though not always specific to the films.

Despite my ethical discomfort with Hanzo's methods, I have to admit to thoroughly enjoying the Hanzo the Razor trilogy, their polished and imaginative blend of the traditional with the perverse making for a genuinely unique viewing experience. But my opening warning remains valid – these are not films for everyone and their archaic sexual politics are guaranteed to cause problems for some viewers, something the BBFC has acknowledged by slapping an 18 certificate on all three of them. But there's so much that is good here and the transfers so impressive that this box set just has to come recommended, especially for fans of Japanese jidaigeki or pinku eiga. Just be careful who you sit down to watch them with.