He first appears during a field trip, being forced by Lee Hyeseong and a group of bullies to fetch them coffee. Because of this, he gets off the bus briefly, claiming he needs to urinate. He sees something strange but dismisses it as a hallucination and returns to the bus, only to be criticized by Hyeseong and the bullies for being disrespectful. As the bus departs, it enters a tunnel to take a shortcut due to the late hour, eventually arriving at the village where sacrifices must be offered to demons. He is calm, quick to assess situations, and righteous, though he is a timid man. He is an old friend of Junyoung and cares deeply for the injured Junyoung.

Dohyun's childhood friend, but he is also being bullied. In the past, students who saw him get hit by bird droppings treated him as 'dirty' and ignored him. Dohyun was the only one who spoke to him, but because of this, Dohyun became a target for bullying instead, while Junyoung ended up ignoring Dohyun to survive. He is severely injured when the bus is struck before being hit by a train. Seeing this, the people who arrived in the demon village earlier say, "Since escaping this village is impossible anyway, we should just offer Junyoung as the next sacrifice."

A male teacher who wears glasses. He is portrayed as a kind person, taking care of the injured Junyoung. When a villager suggests sacrificing the injured Junyoung so others don't have to die, he gets angry, stating that Junyoung is a student in his class. Before going to tend to Junyoung, he instructs the students to tell him if the villagers plot anything suspicious.

A male student in the same class as Dohyun and Junyoung. He leads the bullying against Dohyun. In Episode 2, he tricks Seungchan and Hyeongseok into crossing the boundary line, claiming that since there is only one Watcher Demon, they can't be caught if they run in different directions. He watches without crossing himself. When Seungchan and Hyeongseok are killed by the Watcher Demon, he wets himself in fear and lies to the teacher, saying he tried to stop them. He then spreads a false rumor that Dohyun mocked him for wetting himself, making the other students hate Dohyun. He is a loud-mouthed and rude student.

A man wearing glasses. He is Son Manki's assistant. His occupation before entering the village is unknown, but he is described as a 'skilled technician' and is considered essential personnel for the village. He sighs in relief when the demons eat the sacrifices inside the Sankyeong High School bus. When Manki orders him to take the surviving students to the gym to rest, he tries to guide Dohyun's class, but when the teacher asks for an ambulance for Junyoung, he says there are no ambulances. The next day, he gathers the Sankyeong High students and villagers to introduce them and explains the village rules. When Dohyun, wanting to make alcohol from corn, asks for a distiller, Jungman introduces him to the building where the Demon of Sound resides. He is a cheerful, kind, and playful young man. He has a large build and a somewhat cute personality.

She appears in Episode 3 while stitching Junyoung's wounds. She was a nurse before entering the village, making her essential personnel. When Junyoung wakes up from a nightmare and thanks her, she nonchalantly replies that she is just doing what she can.

He was a car mechanic before entering the village. Because of this, he is considered essential personnel. When Dohyun and Jungman try to build a distiller, he retrieves a thermometer sensor needed for the device from a car. He is close with Jungman.

The leader of the 'Jang Taeseok Gang,' a faction within the village. He was a professional soldier before entering the village. He formed his own faction and competes to ensure its members are not chosen as sacrifices. Watching from afar as Hyeseong frames Dohyun by claiming he was smiling when Seungchan and Hyeongseok died, he remarks, "A real psycho just joined us." In Episode 3, Jungman warns Dohyun, "Jang Taeseok's gang are trash, so don't associate with them." Later, Jang Taeseok appears before Lee Hyeseong, explains the concept of 'essential personnel,' and suggests that since he doesn't want more essential personnel, Hyeseong should vote to sacrifice Dohyun. He promises that if the plan succeeds, five students of Hyeseong's choice, including Hyeseong himself, will be exempt from being sacrificed. He watches Hyeseong argue for Dohyun's sacrifice.

An elderly man. He is an expert in farming and thus essential personnel. When the demons eat five people inside the Sankyeong High School bus, he remarks, "They looked like students; are they all dead?" When the teacher appears and asks what happened to the people on the bus, he informs him they are all dead and asks Jungman to guide Dohyun's class to the gym.