students become trapped at their high school when a science experiment goes disastrously wrong, unleashing a highly contagious virus. Cut off from the outside world, the teenagers must use everyday objects to fight off the infected and survive.Main villain:Gwi-nam. Other prominent villains and antagonists:Lee Byeong-chan: The science teacher who created the Jonas Virus. His desperate attempts to save his bullied son sparked the entire zombie outbreak.Lee Na-yeon: A wealthy, selfish student who deliberately infects a fellow classmate and later tries to sabotage the rest of the surviving group.Min Eun-ji: A bullied student who becomes a "Hambie" like Gwi-nam, using her newfound zombie powers to seek deadly revenge on the entire school.Son Myeong-hwan: The leader of the high school's primary bullying gang, who torments students alongside Gwi-nam in the early episodes.The School Principal: A cowardly and corrupt administrator whose negligence and obsession with the school's reputation contributed heavily to the disaster.protagonist Lee Cheong-san: A brave, quick-witted teen deeply protective of his childhood friend,others: On-jo.Nam On-jo: The co-protagonist and a resourceful student who uses her father's survival training to help her friends.Lee Su-hyeok: An athletic, reformed bully who serves as the group's chief muscle and frontline protector.Choi Nam-ra: The stoic class president who becomes a "half-zombie" and uses her heightened senses to keep her classmates safe.Yang Dae-su: A loyal and kind-hearted student who helps keep the group's morale up.Jang Ha-ri: The badass captain of the archery team who fights her way through the school with her bow.Song Jae-ik: A Hyosan police detective who uncovers the origins of the Jonas Virus and tries to rescue survivors.Nam So-ju: On-jo’s father and a dedicated emergency rescue captain who risks everything to save the children.Park Sun-hwa: Their compassionate homeroom teacher who protects her students at all costs.side characters: Han Gyeong-su (Ham Sung-min): Cheong-san’s loyal, non-wealthy best friend.Lee Na-yeon (Lee Yoo-mi): A wealthy, selfish student who causes early conflict within the survivor group.Yoon I-sak (Kim Joo-ah): On-jo's close friend who gets infected early in the outbreak.Jang Ha-ri (Ha Seung-ri): A skilled archer desperate to find her younger brother.Park Mi-jin (Lee Eun-saem): A foul-mouthed but fiercely protective senior stuck in the school bathrooms.Yang Dae-su (Im Jae-hyuk): The comedic and musical member of the main survivor group.Park Sun-hwa (Lee Sang-hee):The compassionate English teacher who protects her students until her tragic death.Song Jae-ik (Lee Kyu-hyung): A local detective