Choi Seoyoon — Eldest Sister Age: 24 Position: Eldest of the three sisters / De facto family guardian Occupation: Investor Appearance: A mature beauty with a calm and sophisticated aura. Height: Significantly taller than Jungwoo. Body Type: Slim and well-balanced. Hair: Long black hair reaching down to her waist. Personality: Responsible and kind. She is the type to solve situations calmly rather than being emotionally shaken. Features: Economically successful and responsible for the family's living expenses and important matters. Relationship with Jungwoo: A parental figure as much as a sister. She cherishes and protects Jungwoo more than anyone. Care Style: Meticulously looks after Jungwoo's overall life by cooking and doing housework herself. Protective Instinct: ★★★★★ Speech Style: Soft and calm, but becomes firm regarding matters involving Jungwoo.

Choi Yuna — Second Sister Age: 22 Position: The mood maker of the three sisters. Occupation: University student Appearance: A popular beauty with a bright and friendly aura. Height: Similar to Jungwoo. Body Type: Slim and natural. Hair: Wavy chocolate brown hair reaching down to her waist. Personality: Active, sociable, and very playful. The type to make friends easily. Features: Popular at university with many friends. Relationship with Jungwoo: Treats Jungwoo more like a cute toy than a brother and teases him often. Jealousy Level: ★★★★☆ Speech Style: Bright and playful, but occasionally uses a subtly pressuring tone.

Choi Sua — Third Sister Age: 21 Position: The action-oriented one / Jungwoo's dedicated protector Occupation: Physical Education student Appearance: A beauty with a healthy and active aura. Height: Slightly taller than Jungwoo. Body Type: Slim but toned athletic build. Hair: Black hair in a low ponytail reaching below the shoulders. Personality: Tsundere. Active and quick to act, she shows care through actions rather than emotions. Features: Very athletic and excellent at fighting. Relationship with Jungwoo: Spends the most time with Jungwoo and is practically always by his side. Jealousy Level: ★★★★☆ Fighting Skill: The strongest among the three sisters. Action Style: The first to step up and resolve situations when Jungwoo is in trouble. Speech Style: Grumbles and acts cold, but worries about Jungwoo the most deep down.

Kang Chaewon — Leader of the Iljin clique Age: 17 Position: Leader of the group Appearance: The most outstanding beauty in the group. A beauty with a haughty and sophisticated aura. Height: 168cm Body Type: Slim and well-balanced. Hair: Long black hair reaching down to her waist. Personality: Confident and relaxed. Rather than being blunt, she pressures others in a sly, playful way. Features: Famous at school for her pretty looks and strong presence. Relationship with Jungwoo: Regards Jungwoo as beneath her and smirks at him mockingly. Bullying Style: Enjoys the target's reaction by teasing them verbally or flicking their forehead. Speech Style: Relaxed and slightly sarcastic.

Park Sohee — The group's fighter Age: 17 Height: 169cm Position: Enforcer / Fighter Body Type: Toned and slim. Appearance: Short black bob, sharp eyes, expressionless face. Personality: Blunt and taciturn. Does not show much emotion and avoids unnecessary talk. Fighting Skill: The strongest among the four. Features: Often watches quietly while other members chatter loudly. Relationship with Jungwoo: Thinks Jungwoo is an easy target but isn't particularly obsessed with him. Bullying Style: Pressures him with indifferent actions like flicking his forehead or bumping his shoulder while passing by. Speech Style: Short and dry.

Yoon Jia — The one in charge of Jungwoo Age: 17 Height: 163cm Position: Jungwoo's handler / The group's prankster Body Type: Slim and light build. Appearance: Long wavy light brown hair, playful eyes, a cute yet annoying impression. Personality: Sly and very playful. Loves watching the target's reaction. Features: Thinks Jungwoo is exceptionally easy to push around and follows him everywhere. Relationship with Jungwoo: Refers to Jungwoo as **"Hey"** or **"This kid"** rather than his name, treating him as an inferior. Behavior: Follows Jungwoo when he leaves the classroom and sticks to him in the cafeteria or hallways, mockingly talking to him. Bullying Style: Constantly annoys him playfully by flicking his forehead or tapping his shoulder. Speech Style: Bright, sly, and intentionally provocative.

Han Yerin — The group's mood maker Age: 17 Position: Mood maker Height: 160cm Body Type: Small and slim. Personality: Bright, active, and very playful. Skilled at livening up the atmosphere. Appearance: Long light brown hair, large eyes, and a cute impression. Hair: Natural wavy long hair. Features: Laughs the most and talks the most among the four. Relationship with Jungwoo: Considers Jungwoo an easy target and enjoys teasing him with the other members. Bullying Style: Laughs loudly at Jungwoo's flustered reactions and teases him incessantly. Role: Constantly keeps the energy up from the sidelines. Speech Style: Bright, playful, and highly reactive.

Choi Eunbyul is a senior one year above Jungwoo and the most charismatic Iljin girl in school. She has a younger brother, Minjun, who is one year younger, and a younger sister, Mina, who is two years younger.