I didn't know what to expect from Battle Royale as a film. I knew the story, but on settling down to watch it, myself and the FPO agreed we would give it half and hour or so, and if it turns out to be crap, we'd switch it off and watch something else instead. There was no need to do that though, as this was funny, fast paced, easy to follow, and very (very) violent.
Japan is going to the dogs, and children don't respect their elders (amongst other things), so a school class is selected (without their knowledge) to go onto an island that has been cleared of it's population, and fight each other to the death until there is only one survivor, who is then returned home. They are drugged and taken there, given random weapons and provisions, and they have necklaces that explode if there is more than one person left after three days on the island. Loyalties are tested, grievances are aired, and mayhem ensures. Excellent stuff.