Son Sang-yeon as Jang Woo-jin, a student of Class 2-5 and Ha-ri's younger brother.Kim Jin-young as Kim Ji-min, a student of Class 2–5, Hyo-ryung's friend, and member of the school's choir.Kim Joo-ah as Yoon I-sak, a student of Class 2-5 and On-jo's best friend.Ham Sung-min as Han Gyeong-su, a student of Class 2-5 and Cheong-san's best friend, who came from a low-income family.Ahn Seung-gyun as Oh Joon-yeong, the top student of Class 2-5 and the school.Kim Bo-yoon as Seo Hyo-ryung, a reclusive student of Class 2–5.Im Jae-hyuk as Yang Dae-su, a student of Class 2-5 and Woo-jin's best friend.Jeon Bae-soo as Nam So-ju, captain of the Hyosan Fire Station rescue team 1, and On-jo's father.Lee Kyu-hyung as Song Jae-ik, a detective of Hyosan Police Station.Kim Byung-chul as Lee Byeong-chan, a life science teacher and creator of the virus, serving as the series' overarching antagonist.Lee Yoo-mi as Lee Na-yeon, a wealthy but arrogant student of Class 2–5.Yoo In-soo as Yoon Gwi-nam, a school delinquent who is a student from Class 2-1 and the series' main antagonist.Lomon as Lee Su-hyeok, nicknamed "Bare-su", a student of Class 2-5 who is a reformed ex-delinquent.Cho Yi-hyun as Choi Nam-ra, the class president of Class 2–5.Yoon Chan-young as Lee Cheong-san, a student of Class 2–5, he is On-jo's neighbor and childhood friend.Park Ji-hu as Nam On-jo, a student of Class 2–5, she is Cheong-san's neighbor and childhood friend.With no food or water, and communication cut-off by the government, they must use equipment around the school to protect themselves in the midst of a battleground or they will become part of the infected.Ĭast and characters Main cast After a failed science experiment, a local high school is overrun with zombies, and the trapped students struggle to survive.