The story opens with a frantic news broadcast about a young girl being brought back to mainland Japan after she wins the latest "Survival Game Act", a contest that pits high school students against each other in a fight to the death on a remote island.
One year later, class 3-B makes a field trip after completing their compulsory studies; however, the class is gassed on their bus. They wake up in a "briefing room" on a remote island, wearing strange electronic collars. Kitano explains that the class has been chosen to participate in this year's Survival Game Act as a result of the Survival Act, which was passed after 800,000 students walked out of school. The orientation video cheerfully instructs the class to kill each other for three days until only one student remains. Students resistant to their rules or entering one of the randomly placed "death zones" for each day are to be killed by the collar's detonation.