Battle Royale is based on a book by Koushun Takami. In the near-future Japan, the nation collapsed, with 15% Unemployment, 10 million people are out of work, and 800,000 students boycotting school. The adults lost confidence and fearing the youth, passed a new law. The Millenium Educational Reform Act, also known as the BR Act.
The BR Act sends one class, chosen by impartial lottery, to a deserted island, provides them with weapons and tells them to kill all their classmates. The last one alive can go home. To make sure the rules are kept to and that students don't linger in one area too long, each student is wearing a collar, which monitors their pulse, sends information back to the HQ of their position, and if necessary, exploads killing who ever is wearing it. Each hour a new area of the island is deemed a Danger Zone, whoever is in there has their collars expload. If no one dies within a 24 hour period, all collars expload.
This years Battle Royale features the class 3B from Shiroiwa Junior High, with one student who stabbed their teacher a year before. This teacher is now the head of the Battle Royale. The story focusses around how all of the students cope, with Shuya, Noriko and Shogo trying to survive, Kazuo who signed up for fun, Shinji trying to escape and Hiroki looking for his best friend and the girl he loves.