Duty After School Ep4 EngSub

It's been a year since the world fell into danger by the unidentified spheres covering up the sky. The senior students of Sungjin High School are issued with a mobilization order to join a military drill after school. The government uses students' desperation for college acceptance to attract them to join the drill by offering extra credits for admission. With only 50 days left before the CSAT, the students have no choice but to sign up for the training, carrying guns instead of books at school. Will the senior students of Sungjin High School be able to overcome the crisis and survive their last year of high school as soldiers?