A 1st-year student in Class A at Zombie High School. He is a righteous protagonist, a hero, and a model student who is an idol to everyone. He is fundamentally kind to all students. He has a crush on Lee Yuri. He uses a steel chair as a weapon.

A 1st-year student. A literary girl who loves books. She reads extensively and is knowledgeable in various fields. She has a calm and considerate personality, though she can be a bit clumsy and airheaded at times. She is unaware that Nam Dongjin likes her. She uses a syringe as a weapon and provides healing with a first-aid kit.

A 1st-year student. She is very energetic and positive, possessing a personality that gives strength just by looking at her. She is a cheerleader. Her weapons are a megaphone and cheerleading pom-poms.

A 1st-year student. He is a student completely immersed in his own world. He interprets everything happening in reality through a fantasy worldview. He uses a broom and a dustpan as weapons.

A 1st-year student. He is youthful and childish for his age. He loves skateboarding. His weapon is a squeaky toy hammer.

A 1st-year student. She is bright and cheerful. She loves snacks. Her weapon is a bottle of cola with Mentos in it.

The kind principal who is always a pillar of support for the students. He speaks to students politely. He goes into a frenzy after Baek Seolhyun (Witch Trilogy), who had fallen and collapsed in the elevator, dies. Later, he confronts the students who intrude while he is facing off against Jeong Dongseok on the rooftop.

The appearance of Principal Samuel after awakening. It is said he went into a frenzy, consumed by emotions that reacted with the serum. He breaks the rooftop railing with a spectral entity and begins the battle with the group. The zombie spectral entity behind him performs the primary attacks.

A mysterious student who transferred to Zombie High School. He joined 1st-year Class A, where the core figures of the story are gathered. He never tries to mingle with others and is occasionally spotted in suspicious areas of the school. He wears a uniform from a different school.

A 1st-year student. Her personality is very prickly and sharp. As her profile suggests, she is awkward at receiving kindness or approaching others, and she believes she prefers being alone. She secretly looks out for Jeong Dongseok.

The first principal who founded Zombie High School and the wife of the current principal, Samuel. She wanted to plant hope in others so they could be as happy as she was, showing a pure and lively side. Unlike her human form, her skin has turned gray, her clothes are torn, she has three faces, a long protruding tongue, and six arms, having transformed into a horrific figure. After becoming a zombie, she died from falling down an elevator shaft.