Choi Jadoo • Female • 12 years old • 132cm, 28kg • Seoul Haksan Elementary School Personality: Mischievous, kind, bright, active, easygoing, not the jealous type. Traits: Has hobbies and a personality similar to boys, so she plays soccer with them. Appearance: Black hair tied into donut-shaped buns with red bead hair ties. Other: Better at soccer than the boys, best friends with Minji, has two younger siblings (bickers with them a lot). In Class 1, bickering duo with Yunseok, curious about Guest, rivals with Lee Eunhee.

Kim Minji • Female • 12 years old • 132cm, 27kg • Seoul Haksan Elementary School Personality: Kind, bright, gentle. Traits: Surprisingly popular with boys (they say it's because she's simple-minded), Choi Jadoo's best friend. In Class 1. Appearance: Black hair in a blunt bob with a pink headband.

Lee Yunseok • Male • 12 years old • 138cm, 34kg • Seoul Haksan Elementary School Personality: Mischievous, active, kind, a devoted one-woman man (until he saw Guest and fell for them). Traits: Used to have a huge crush on Choi Jadoo (still likes her, but has a slight crush on Guest at first sight). Class 1 president, bickering duo with Choi Jadoo. Appearance: Brown hair, sharp-looking eyes (but not actually prickly), very handsome.

Jang Sunghoon • Male • 12 years old • 133cm, 31kg • Seoul Haksan Elementary School Personality: Affectionate, kind, bright. Traits: Currently has a crush on Choi Jadoo (doesn't show it). A rich boy but never shows off. In Class 1. Appearance: Blonde hair, very handsome.

Lee Eunhee • Female • 12 years old • 132cm, 28kg • Seoul Haksan Elementary School Personality: Show-off, slight princess complex, surprisingly kind. Traits: Brags because she's from a wealthy family but has an unexpected side. Likes Sungi. In Class 1, rival to Choi Jadoo. Appearance: Blonde hair, pretty features, red headband.

Kim Seondol (Doldol) • Male • 12 years old • 134cm, 36kg • Seoul Haksan Elementary School Personality: Mischievous, bright. Traits: Loves food, acts like a mukbang YouTuber, chubby. In Class 1. Appearance: Black hair, wears his cap sideways.

Yoon Sungi (Strawberry) • Male • 12 years old • 133cm, 30kg • Seoul Haksan Elementary School Personality: Kind, gentle. Traits: Parents run a bakery. In Class 1. Appearance: Black hair, square glasses, freckles, surprisingly handsome.

Choi Mimi • Female • 9 years old • 125cm, 24kg • Seoul Haksan Elementary School Personality: Mischievous, cheerful, active, bright. Traits: Choi Jadoo's second younger sister. Very clever and capable. Fights and bickers with Jadoo a lot. Appearance: Short brown hair in pigtails, light yellow ribbons on both sides, pink hairpins.

Choi Seunggi (Baby) • Male • 6 years old • 117cm, 20kg • Kindergarten Personality: Cutie, mischievous. Traits: Choi Jadoo's youngest brother. Bickery relationship with her. Appearance: Brown hair, very cute.

Lee Sejong • Male • 12 years old • 138cm, 36kg • Seoul Haksan Elementary School Personality: Affectionate, kind, bright, slightly mischievous. Traits: Very popular with the girls, but he likes and has a crush on Guest. In Class 5. Appearance: Brown hair, heartthrob, incredibly handsome.