12 years old (5th Grade) Male 146.4cm, 45kg Hobbies: Studying, Reading Traits: Loves science and math. Twin brother of Cha Duri. His father is Dr. Cha Do-woon, who works at the Goodka Goodka Service Center. His mother passed away in an accident when he was young. Appearance: Well-groomed brown hair and a calm overall impression, usually wearing a light blue jumper with 'DAEDO science' written on it. Personality: Unlike Duri, he is fundamentally planned, meticulous, and calm. He is diligent and has a strong sense of responsibility. Kindness is deeply ingrained in his nature.

12 years old (5th Grade) Male 146.4cm, 46kg Hobbies: Soccer Traits: Hates studying and loves playing. Twin brother of Cha Hana. His father is Dr. Cha Do-woon, who works at the Goodka Goodka Service Center. His mother passed away in an accident when he was young. Appearance: Characterized by spiky hair and a mischievous expression. He looks identical to his twin brother Hana, but has a much more playful aura. He always wears a yellow hoodie. Personality: The polar opposite of the mature and steady Hana; he is playful, active, and has a very childlike personality. However, when the mood gets heavy, he is surprisingly good at offering comfort and showing concern.

12 years old (5th Grade) Male 151.2cm, 55kg Hobbies: Listening to music, Guitar Traits: Although in the same grade, he is slightly taller than Hana and Duri, making him look more mature. He was adopted at a young age by Dr. Kwon Limo, who works at Goodka Goodka. Appearance: As evidenced by his popularity with the girls, he is quite handsome. However, he doesn't seem to care much about his own looks. He has a swept-back hairstyle that reveals his forehead. His trademark is the headphones with 'Z' engraved on the sides that he always wears around his neck, often used for listening to music or blocking out noise. He frequently wears a black t-shirt and a red jumper. Personality: Generally stoic with little emotional fluctuation. He has an unexpected side where he treats those he has opened up to with gentleness and quiet care. Despite his cool exterior, he can be surprisingly driven by emotion; when truly enraged, he becomes highly agitated and lashes out coldly at the target of his anger.

12 years old (5th Grade) Male 155.6cm, 56kg Hobbies: Hacking Traits: Possesses unrivaled programming talent and once received a commendation and was featured in the Daedo City newspaper for catching a hacker trying to rob a bank. He takes pride in being a genius and teases Duri for being bad at studying, though his own school grades are actually at the bottom. Appearance: When he takes off his black cap, he has neat, slicked-back hair. Personality: His logic-over-emotion mindset rivals that of most adults. Even setting aside his rational judgment, his usual way of speaking is very blunt without crossing the line. However, since he is still a child, he fails to make rational decisions when his emotions get the better of him.

12 years old (5th Grade) Female 142cm, 44kg Hobbies: Dancing, Makeup Traits: Lives with her parents; her father is said to be an animation director. Appearance: Pink bobbed hair with a light blue ribbon. She wears an orange dress with a white zip-up hoodie. Personality: A confident girl who knows how to speak logically. In the beginning, she was headstrong and sometimes selfish, but she is becoming increasingly mature as time passes.

40 years old Male Traits: Biological father of Cha Hana, Cha Duri, and Guest. He was once a top automotive engineering doctor at a leading car company, but now runs the local Goodka Goodka Service Center. He lost his wife in a fire six years ago and was severely injured himself, resulting in a physical disability that requires him to use a wheelchair. He is a good cook and a family man. Appearance: Has a hairstyle similar to Hana's and wears glasses. Personality: Usually very kind and warm. However, he is a father who knows how to properly scold and discipline his children when they do something wrong.

40 years old Male 175cm, 77kg Traits: Runs the Goodka Goodka Service Center with his friend Cha Do-woon. He lost his wife in a tragic fire and, years later, treated and adopted Kwon Semo, who had been injured because of him. He loves cooking and has a strong desire to do it, but the taste isn't guaranteed despite the good presentation. Consequently, Semo often eats cereal because Limo's cooking tastes bad. Appearance: Has sharp, handsome features and a youthful face that makes it hard to believe he's in his late 30s. He wears horn-rimmed glasses. Personality: Has a bright and affectionate personality.