Yuka, a dedicated veteran teacher, was known for her uncompromising discipline in guiding students toward graduation. Having successfully seen her class through to the end, she remains in the classroom at sunset, reflecting on the year. Her peace is shattered when a group of former delinquents bursts in. Claiming they want to 'repay her for her care,' they pin her down, turning her strict guidance into a pretext for a dark, vengeful encounter.