The protagonist of this work. A 2nd-year high school student who is frequently targeted by her classmates for the 'Dare Game,' though she personally fails to understand what is so fun about it. Given the frequent mentions of her beauty in the story, she appears to be a very pretty girl. She likes Seok Jinwon because she feels he is the same kind of person as her, but her affection seems somewhat off-kilter, likely due to the nature of the mental illness she suffers from. She is presumed to have Antisocial Personality Disorder, characterized by a severe lack of social skills, empathy, and morality. Her condition is serious enough that she takes psychiatric medication. Because of her inability to understand others' emotions, she troubles those around her in misguided ways; ironically, this trait draws the jealousy of Hwang Subin, who desperately craves to be seen as a 'psycho' by their peers. When she misses her medication, her impulse control seems to drop significantly. She exhibits extreme behaviors such as betraying Song Jaemin—who was trying to help her—to escape a disadvantageous situation, suddenly confessing to Seok Jinwon, or spending all her money on food due to an uncontrollable appetite. Her mother died of an illness early on. If her mother's death is discovered, she will have to live at her father's house; to avoid this, she is currently concealing the body inside a kimchi refrigerator. Another part of her past was later revealed: in elementary school, she locked a child who was kind to her in a warehouse for 30 hours to keep them from coming to school. When the police arrived the next day and asked why, she gave the absurd reason that she wanted to eat all the globe-shaped jellies by herself. It appears she was hospitalized in a psychiatric ward for three years because of this incident.

The instigator of the Dare Game and the leader of the group. She exhibits strong traits of Histrionic Personality Disorder, intentionally acting like an eccentric person to draw attention. While she appears energetic and confident on the surface, she is actually constantly struggling and feeling anxious to be recognized as special. The reason she is obsessed with Yu Sarang is that Sarang receives more attention from their classmates for having a 'stronger' psycho image. she is an arts major and has been attending an entrance exam art academy since middle school. Judging by how she bets 50,000 won on the game, her family seems to be quite wealthy.