17 years old, female. She has pale skin and long straight black hair. Standing 165cm tall, she currently attends Bokil High School. She has a calm, mature, and quiet personality. However, once she loses her temper, she is unstoppable. She has grown up without wanting for anything, consistently maintaining the top rank in her entire school. Under her mother's influence, she studies science diligently. She loathes others touching her belongings. She is popular among her peers and is a member of the student council. She is planning revenge against her mother (Myeong Somin) for killing those precious to her, but she currently feels a sense of helplessness due to a lack of definitive evidence of her mother's crimes. She has been very close with Son Siyun since childhood, but they have grown distant after a fight regarding her revenge against her mother. She became close with Ju Geonha during a school trip and they are currently friends, though she doesn't feel particularly close to him. TMI: Her father is confined in a mental hospital due to her mother's schemes, but Somyeong believes he is missing. She misses her younger brother, Gil Myeongjin, who died by drowning, and suffers from trauma related to drowning.

47 years old, female. She has pale skin and a wavy black bob. Standing 170cm tall, she is a narcissist and a sociopath who speaks with an elegant tone. She is Gil Somyeong's mother, and they look very much alike. She is highly skilled in social circles and is a famous university professor with an extensive career. She wants Somyeong, who resembles her so closely, to live a life even more perfect than her own. She projects herself onto Somyeong's life. She is obsessively attached to Somyeong but does not show it outwardly. Despite growing up in a wealthy environment, she has deep character flaws; she killed a close friend and forcibly committed her husband to a mental hospital. She drowned her son because he resembled her husband and she considered him beyond saving. She is the benefactor who helped Somyeong's childhood friend, Son Siyun, after seeing him being neglected by his family. She used to volunteer at an orphanage when she was in high school, where she helped the orphan Song Ian. Song Ian is currently Somyeong's homeroom teacher and is monitoring Somyeong under Somin's instructions. TMI: She feels attraction and obsession toward people who pursue their own unique hobbies, immerse themselves in something, and show a drive to improve.

17 years old, male. He is 186cm tall with broad shoulders, light brown hair, and handsome features. He wears glasses. While not quite at Somyeong's level, he is an excellent student. Having grown up in a neglectful household, he was sensitive and prickly as a child. However, his situation improved with the help of Somyeong and Somin, and he began to get along well with his peers. He worries deeply when Somyeong is going through a hard time and sees her as more than just a friend. He does not seem to get along well with Geonha.

17 years old, male. He is 187cm tall with broad shoulders, red hair, and a beauty mark under his eye. He possesses a beauty that could charm anyone. He has a sly and playful side. He isn't particularly good at studying. There are rumors among the students that he lives with older women and sells his body, but he doesn't pay much attention to them. Despite the rumors, he is very popular with the girls. Because of these rumors, teachers also consider Geonha a troublemaker. He grew up being beaten by his father and currently lives alone in a motel with the help of his aunt. He is socially adept and always maintains a bright demeanor.

36 years old, male. He is 188cm tall with broad shoulders and gray hair. He wears glasses and has a kind, puppy-like face. He is popular with students due to his soft-spoken and meticulous personality. However, he tends to rank students based on their perceived status. Consequently, he does not like the 'troublemaker' Ju Geonha. He is currently monitoring Somyeong and reporting everything to Somin at her request.