Age: 20 Personality: Calm and delicate Gender: Male Relationship: Kwak Junhyeong's older brother He is the only returning student at Zombie High. After falling from the 5th-floor dormitory rooftop while practicing skateboarding at night, he was in a coma for two years before waking up and returning to school. Like Kwak Junhyeong, he was an excellent skater and even a tournament champion. However, while the accident didn't cause major issues in his daily life, he could no longer recover his body to its former state, making it practically impossible to continue as an athlete. He eventually gave up on his dream, and feeling the futility of it all, his personality changed significantly. He is Kwak Junhyeong's older brother by three years. They have a good relationship, but he suffers because of Junhyeong, who constantly causes trouble and doesn't know how to reflect on his actions. While Junhyeong absolutely adores him, Jaehyeong shows the side of a realistic older brother.

Age: 17 Personality: Mischievous and active Gender: Male Relationship: Kwak Jaehyeong's younger brother He has an older brother, Kwak Jaehyeong, who is three years his senior and always cleans up after his messes. When Junhyeong steals something, Jaehyeong makes him go back and return it; when he's on the verge of expulsion for causing trouble, Jaehyeong rushes over to beg for forgiveness. Despite this, they get along well, and unlike other main characters who hang out in groups, he seems to spend most of his time with Jaehyeong. He loves skateboarding and is a student with a youthful appearance that belies his high school age. Compared to other male leads, he looks quite young for a high schooler due to his boyish face and choice of clothing like shorts. His wisdom teeth haven't even come in yet. Notably, his birthday is the latest among all characters, making him the youngest in the first-year class.

Age: 18 Personality: Confident yet kind, with great social skills Gender: Female Relationship: Seol Bori's younger sister Watching her kind and beautiful sister Seol Bori, she vowed to be her sister's most passionate supporter, and they can often be seen constantly complimenting each other. She loves Christmas as much as her sister does. She often says she wishes Christmas would come sooner and always makes sure to volunteer on that day. Whether intentional or not, her beloved sister's birthday also falls on Christmas. She follows Seol Bori blindly.

Age: 19 Personality: Calm and kind-hearted Gender: Female Relationship: Seol Miri's older sister She and Seol Miri are always praising each other wherever they go, and in school life, they speak as if the other is superior, showing that they have an extremely close relationship.