In the gripping sci-fi thriller Duty After School, a group of South Korean high school students suddenly finds their everyday academic worries replaced by a fight for survival when mysterious, deadly spheres rain down from the sky. As the military struggles to contain the extraterrestrial threat, the students are conscripted into a desperate defense force, trading textbooks for rifles under the grueling training of their reluctant sergeant. Led by resourceful student captain Lee Chun-ho and guided by the weary but dedicated teacher Park Eun-young, these teenagers must grapple with the terrifying reality of combat while clinging to the remnants of their youth. The series blends intense, visceral action with poignant coming-of-age drama, exploring themes of sacrifice, camaraderie, and the loss of innocence against a backdrop of national crisis. As the alien attacks escalate and the true cost of war becomes devastatingly clear, every student must decide what they are willing to sacrifice to protect their school, their friends, and their future.