It's Akira Kurosawa's eighth film, but the first one he regarded as really his. Until then, he'd been doing what his studio told him to. It's also the first of his sixteen collaborations with Toshiro Mifune, so in other words it's kicking off one of the most famous partnerships in cinema history.

It's pretty cool. Thankfully it doesn't have any samurai, but instead is set in post-war Japan during the American occupation. (Kurosawa was banned by the censors from referring to this, but he managed to sneak in a few subliminal digs anyway.) Takashi Shimura is an alcoholic doctor with anti-tact, who shouts and throws things at his patients. Mifune is a young yakuza too macho to admit that he has tuberculosis. Sounds good, right? It is. Unsurprisingly they're an explosive combination, with Shimura almost proud of a bedside manner that's surely going to get him killed and Mifune looking likely to be the one who murders him. Mifune usually leaves Shimura's clinic having either just tried to throttle Shimura and/or been kicked out by him.

The film was originally going to be about Shimura's character, but Kurosawa was so impressed by Mifune that he expanded his role and so the second half of the film becomes more about yakuza. This makes the second half more exciting, but personally I liked the less violent first half just as much. Shimura made me laugh. He's so childish! I'm a massive Takashi Shimura fan anyway, so if anything I was happier when the film was about him.

The film's got a social conscience, unsurprisingly from Kurosawa. It's metaphorically about Japan, still recovering from the war. Both Shimura and Mifune are playing characters who are largely to blame for their own problems and could at any time have simply decided to sort themselves out, but don't have the willpower. They're stubborn and not making it easy to like them, yet could both also be called apathetic in how they've accepted their fate. What's more this is reflected in the world around them, with the camera being endlessly drawn to a disgusting pond in which children play and yet all kinds of rubbish and pollution is dumped. Is it a bomb crater? A reservoir? I don't know. They're living in a black market slum and the only reason it doesn't have burned-out buildings is that the censor wouldn't have allowed them.

This isn't subtle, but if anything it's not going far enough. Mifune for instance had only returned home from military service in 1946 and really looked as if he was dying of tuberculosis, being so poor that he made a suit out of his military-issue blankets.

It's also worth pointing out that tuberculosis was a major killer at the time. It had got really bad during the war, which of course ended with about three million dead, nine million homeless and much of Japan either nuked or firebombed to ashes. The post-war government took measures to control it, greatly improving both the incidence and death rate, but even so the annual risk of infection was estimated to be four per cent in the 1950s.

Then there's Kurosawa's use of illness and contagion as a metaphor. Gangsters are likened to "a rotten maggot... infested with bacteria". Their world is corrupt and ruled by thuggery. Interestingly Shimura even bashes traditional macho masculine values, despite their being practically worshipped by Mifune. Shimura says to Mifune's face that he's the "worst kind of coward" and that his gangster lifestyle is "feudalistic loyalty crap". Nevertheless Mifune really believes that honour and loyalty code of the yakuza, which goes on defining his behaviour even after he's learned that not all of them believe their own bullshit. Is he a good man? No. Does he stand up for and represent the values that Shimura is so contemptuous of? Yes, in his broken, stupid way, but you'd have to be deranged to think that Kurosawa is using him to extol them.

That probably sounds heavy, but this isn't a heavy film. You wouldn't call it light and fluffy, but Shimura is endlessly entertaining and I could have watched him fight with Mifune all day. It's also a pretty good gangster flick. It doesn't have much of a body count, but both of our heroes are dicing with death pretty much throughout and Kurosawa knows how to make his yakuza menacing.

There's also a German Expressionist silent dream sequence. That was surprising.

Despite what you might be thinking, the movie also isn't pessimistic. It's fiercely critical of the world, but Shimura also has a 17-year-old patient who's pretty, cheerful and does everything he tells her. She's still there at the end and she's beating TB, even if no one else is. I really enjoyed this film, actually. It's kind of fun, in a way I don't get from three-hour samurai epics. I like the way Kurosawa's so single-minded in his pursuit of corruption and imperfection, for instance ordering repeated rewrites to make Shimura's character less "clean". In the end he's a stomping bear of a man, shooting his mouth off as if he has a death wish and telling us about how he used to pawn his clothes to pay for prostitutes. Recommended.

"Japanese make so many pointless sacrifices."