The film opens with a handy bit of exposition, which is repeated verbatim below:

At the dawn of the millennium, the nation collapsed.
At 15% unemployment, 10 million were out of work.
800,000 students boycotted school.
The adults lost confidence, and fearing the youth, eventually passed the Millennium Education Reform Act.
AKA: The BR Act.

Every year, a class of teenagers is dumped onto an evacuated island, armed, and told to fight it out. Only one may leave the island, not as a victor, but as a warning of the lengths the state is willing to go to in order to maintain control.

On first reading of the premise, it's tempting to assume that the film is going to be nothing more than a special effects extravaganza whose entertainment value is limited only by its budget and how far the film is willing to go.

To assume this, of course, completely misses the point of the film.

The film proper starts with a media scrum closing in on a helicopter carrying the latest survivor of the Battle Royale - a blood drenched girl who's clutching her rag doll… and smiling. Clearly the BR Act isn't the unmitigated success that the lawmakers were hoping for, which immediately raises another question.

There are plenty of real-world examples of a government promising itself into a corner and then coming up with an unbelievably bad law to extricate itself. So it doesn't require too much suspension of disbelief - for me, at least - to run with the idea of a government manoeuvring itself into a position where it passes a law forcing teenagers to kill each other in an attempt to stop the nation becoming "no good". So far, so good… but this then brings us to the smiling girl.

If the BR Act isn't working - which this scene seems to suggest - then wouldn't the government start looking for alternatives?

I'm tempted to suspect not. My suspension of disbelief isn't very much challenged by the idea that to pass an act like this, the government would have to take a deliberately hard-line stance. And, the problem with hard-line stances is that, once taken, they are very difficult to back down from without losing face - so it is pertinent to ask whether not losing face is worth 40 teenage lives each year.

And when you look at it like that, 40 kids out of an entire population isn't really that many.

So finally, after a bit of scene setting on the part of the film and much digression on my part, we get past the opening credits and start to meet the characters - including Shuya, an orphan, who's father's suicide note ("Go Shuya!! You can make it, Shuya!") must rank as one of the most badly timed attempts at encouragement, ever.

We then reach what is probably the weakest part of the film - getting a class of 40 teenagers onto the deserted island. This is achieved by organising a bogus school trip and then gassing the bus. So that this is an airtight bus? Even if such a thing existed, it seems a bit much to accept that not one of these 40 teenagers turned on the ventilation?

The driver and other staff are wearing gas masks when the gas hits. Granted, this is supposed to happen inside a tunnel but… in pitch black? Somehow I doubt it, in which case someone would have noticed the gas masks going on and the whole ruse falls apart.

And then there is the "school trip" ruse itself. Given that the BR Act has being going for several years, and gets heavy media coverage - as demonstrated by the media scrum in the opening scenes - surely truancy would rocket around 'Battle Royale time', regardless of what school trips were on offer.

It's a short sequence and it quickly progresses the plot to where we need to be, but given the tightness of the scripting elsewhere, the holes here really do jar badly.

When the pupils regain consciousness, they find themselves in a darkened classroom in an abandoned school, confused, disorientated and frightened - not least by irremovable necklaces with which they have all been fitted.

Their state of mind isn't much helped by the arrival of their former teacher, Kitano (Beat Takeshi), who introduces the class to a couple of 'transfer students' and informs them that they are the lucky contestants in this year's Battle Royale Survival Program.

Granted, a lot of what Kitano tells the class is expository in nature - you would expect them to know the background and provisions of the BR act - but he also serves to bring home to the startled students the reality of their situation.

He also puts on a video to explain the rules to the students.

This is one of the most darkly comic moments of the film, as the perky video presenter brings the unbridled enthusiasm of a game show host to counterpoint the increasingly violent events in the classroom.

Finally, the students are called out one by one, handed a bag containing food, water and a random weapon, and sent out into the night.

What follows is seventy-five minutes of the most gut wrenching violence I have sat through in a long time. Not because of the amount of gore - there are plenty of splatter movies out there which will delight spraying far more blood and guts at the screen than this film - and not just because the victims and killers are all children - although this does lend an edge.

What makes the violence in Battle Royale truly shocking is that there are no throwaway characters in he film.

The students are all given rounded personalities - not always deep, but enough. Their reactions - despair and suicide, banding together in search of a way out and even Mitsuko's rampage all fit with their characters and motivations.

And throughout the carnage, we have Kitano - reading off the death toll in a manner you'd normally expect to hear during the football results.

It's impossible not to care about the characters as friendships untangle and new alliances are formed as hopes are raised - only to be blown away by the ever present paranoia engendered by the nature of the game. And, of course, caring about the characters makes their inevitable deaths both shocking and disturbing.

Battle Royale, more than anything else, stands as a warning. Democracy is vulnerable, in a way that authoritarian systems are not, to extremists, populists and the need on the part of our political leaders to be seen to be "doing something". It would be easy, when a threat to our way of life is perceived, to overreact and pass our own Millennium Education Reform Act - destroying what we hold dear in it's own defence.

Review by Paul Pritchard