Gender: Male. Age: 11. Personality: He is not bound by social norms and speaks his mind without hesitation. He is also persistent, trying to find out everything he is curious about until the end. Features: Spiky, shaggy hair. Physique: 138cm, 37kg, Blood Type AB. Likes: Money, Hyuk, robots, Doyoon, Ronaldo, PE, chicken, games. Dislikes: Challenges, studying, laws, violence. Future Dream: Excavator operator, rich man. Nickname: Buzzcut. Family: Yoon Kwangchul (Father). Weaknesses: Word chain games, multiplication tables.

Gender: Male. Age: 30s to early 40s. Seojun's father. He is a high school graduate working as a truck driver and site laborer. He lives with Seojun in Unit 310, Building 101 of the Hankook Villa (a corridor-style apartment). While not in extreme poverty, he is on the poorer side of the working class. He has a stubborn 'old man' (kkondae) streak and is a miser; despite having a working air conditioner, he refuses to use it. When Seojun finally begs to turn it on, he scolds him. Curiously, he stays silent when Seojun swears, but gets so triggered by the request for AC that he threatens to kick him out. He is the type of adult who tells a complaining Seojun things like, "If you just stay still, it's not hot at all," or "You should be grateful you were born in Korea, other countries are..."

Gender: Female. Age: Mid to late 40s. Features: Yoon Kwangchul's older sister. Personality: Like her brother, she has a bit of a temper, but she gets along well with the family and has a kind heart. Given Seojun's way of speaking, one might expect her to scold him harshly, but since she knows that's just how he is, she lets most things slide unless he truly crosses the line.

Yoon Seojun's paternal cousin and Yoon Kwangchul's nephew. He communicates through gestures like nodding or shaking his head, suggesting he either has a speech impediment or is extremely shy. His age isn't revealed, but he appears to be 2-3 years younger than Seojun. He has a very close relationship with Seojun; Seojun once gave him a cherished spinning top, and Hanbyul still treasures it like a symbol of their friendship. (However, he is a bit abnormal—a pervert.)

Gender: Female. Age: 26. Features: Yoon Seojun's stepmother. She cares for Seojun deeply and lives with Yoon Kwangchul. She is kind and very beautiful. A middle school dropout, her father is currently in prison for domestic violence and her mother has passed away. She was bullied in middle school, which led to her dropping out. It is implied she worked in a hostess bar from her teens until age 24. She currently works at a mask pack manufacturing factory. She likes kangaroos.