Full Name: Na Dae-jin Age: 10 Height: 151cm Residence: Apartment in Seongsan-dong, Mapo-gu, Seoul School: Hanbit Elementary School, 4th Grade Characteristics: A 4th grader and a troublemaker who causes frequent accidents due to excessive mischief and talks back to adults without hesitation. He likes to act tough in front of friends to get attention and disregards school rules or public order. When his faults are pointed out, he starts with excuses, but since his father is strict, he tends to lose his momentum in front of him. His mother often covers for his behavior, leading to a difference in parenting styles.

Full Name: Lee Su-jin Age: 38 Height: 164cm Residence: Apartment in Seongsan-dong, Mapo-gu, Seoul Vehicle: None Characteristics: Na Dae-jin's mother and Na Jeong-hun's wife. She has an excessively strong attachment to her son and tends to shield him even when he causes trouble, saying, "He's just a child." When the school or other parents point out Dae-jin's faults, she raises her voice and takes her son's side before checking the facts. Because she doesn't properly restrain Dae-jin's rude behavior, she frequently clashes with her husband Jeong-hun over education issues.

Full Name: Na Jeong-hun Age: 41 Height: 181cm Residence: Apartment in Seongsan-dong, Mapo-gu, Seoul Vehicle: Hyundai Palisade (Gray, 2022 model) Characteristics: Na Dae-jin's father and Lee Su-jin's husband. He is usually calm and responsible, but very principled regarding his child's education. If Dae-jin harms others or acts rudely, he demands an apology and accountability first rather than shielding him just because he's the parent. He especially dislikes lying, evasion of responsibility, and shifting blame. He firmly restrains his wife when she overprotects Dae-jin. He disciplines through appropriate consequences for mistakes rather than corporal punishment.

Full Name: Kim Si-woo Age: 10 Height: 153cm Residence: Apartment in Seongsan-dong, Mapo-gu, Seoul School: Hanbit Elementary School, 4th Grade Characteristics: A classmate of Na Dae-jin. He has a cool and calm personality and speaks bluntly, but he is an ordinary kid who is interested in street fashion and maintains basic manners and boundaries. He naturally helps friends in trouble and admits his own mistakes. He doesn't react much to Dae-jin's simple antics, but if Dae-jin bullies other students or causes a nuisance, he steps in, saying, "Hey, that's crossing the line."

Full Name: Kim Seo-yeon Age: 29 Height: 166cm Residence: Detached house in Mangwon-dong, Mapo-gu, Seoul Vehicle: None Characteristics: A teacher who is friendly and warm to students but maintains principles in guidance. She is usually comfortable enough to joke with the kids, but she firmly disciplines behavior that harms others or repeatedly violates school rules. A beauty with a pure appearance. Even when Na Dae-jin causes trouble, she checks the situation first and makes him admit his faults and apologize directly rather than just scolding him blindly.