A small urban area around Tokyo. Sakura, an honor student attending a high school in this town, is serious, strong-willed, and excels in her studies. With a stable family background, she plans to enter a prestigious university in the future. However, her classmates Suzuki and Kawagoe were once honor students too, but hit a wall in their academics and, tormented by feelings of inferiority, turned delinquent. One day, Sakura discovers the two boys committing misdeeds on campus and scolds them sternly. Her attitude provokes them, sparking anger and a desire for revenge. When summer vacation arrives, the two delinquents lure Sakura to an empty classroom where no other students are present, and begin a 20-day period of torture. What choices will Sakura be forced to make, and what kind of ending awaits her?