Duty After School (Korean: 방과 후 전쟁활동) is a 2023 South Korean military sci-fi thriller dystopian teen drama television series created by Lee Nam-gyu [ko], written by Yoon Soo and directed by Sung Yong-il.

The series stars an ensemble cast including Shin Hyun-soo, Lee Soon-won, Im Se-mi, Kwon Eun-bin, Kim Ki-hae, Kim Min-chul, Kim So-hee, Kim Su-gyeom, Kim Jung-lan, Moon Sang-min, Shin Myung-sung [ko], Shin Su-hyun, Shin Hye-ji, Ahn Da-eun, Ahn Do-gyu, Yeo Joo-ha [ko], Oh Se-eun, Woo Min-gyu, Yoon Jong-bin [ko], Lee Yeon, Ji Min-hyuk, Choi Moon-hee [ko], Hong Sa-bin, and Hwang Se-in.

Based on the webtoon of the same name by Ha Il-kwon, which was later serialized on Naver Webtoon, it is about "purple objects" that appear in the skies around the world and attack humans, so students become cadets to fight against the strange creatures.

[1] Studio Dragon together with director Sung Yong-il, who directed Class of Lies (2019), and writer Lee Nam-gyu, who wrote The Light in Your Eyes (2019), produced the popular webtoon Duty After School [ko] into a drama.

[29] Shin Hyun-woo and Hwang Se-in confirmed their appearance for the series in August and October 2021, respectively.