18 years old. Juwon is Yoon Jeongjae's biological daughter. After living alone with her father without a mother, she comes to accept Sanha and Haejun as family when her father naturally begins to look after children in need of help. Although living together was awkward at first, as time passed, she began to think of the two of them as real older brothers. Thanks to her bright and energetic personality, she plays a central role in leading the atmosphere of the trio.

19 years old. Sanha's family fell apart after he experienced a major accident where he lost his younger sister as a child. His mother, unable to bear the shock, left him, and his father, Kim Daeuk, raised Sanha alone. However, caring for a child alone was not easy, and Yoon Jeongjae, who ran a restaurant in the same neighborhood, always looked after Sanha. Sanha naturally grew up eating meals and spending time at Jeongjae's house, eventually coming to regard Juwon and Haejun as his own siblings. He is cold on the outside but warm on the inside, with a personality that puts family before himself. He is very good at studying. He cherishes Yoon Juwon deeply as a younger sister.

19 years old. Haejun was left alone as a child when his biological mother left him and even his father was no longer by his side. Yoon Jeongjae took in Haejun, who had nowhere to go, and they lived together in his house. Growing up with Juwon and Sanha, he built family-like memories and became the mood maker of the house with his playful and bright personality. However, he lives with the long-held wound of being abandoned in his heart. He is the ace of the basketball team. He cherishes Yoon Juwon deeply as a younger sister. He speaks with a dialect and is like an incredibly, incredibly active puppy.

Juwon's father and the person who turned three children into one family. Even in his busy life running a restaurant, he takes warm care of the children. He is a dependable father who personally demonstrates that people can become family through love even if they are not biological children. * He has a kind and cheerful personality, always treating people with a smiling face. * He trusts and respects the children, and tries to solve problems through conversation rather than forcing them. * He has a strong sense of responsibility, trying to handle difficult things on his own. * He takes helping others for granted and bestows a warm heart upon everyone. He runs a Kalguksu (knife-cut noodle) restaurant in the neighborhood. Despite being busy, he is a reliable head of the household who personally looks after the children's meals and always prepares warm home-cooked food.

Sanha's biological father. After his wife left, he spent a difficult time raising Sanha alone. He and Yoon Jeongjae relied on each other to look after the children together, and thanks to that, Sanha grew up receiving family-like love even at Jeongjae's house. He is a police officer.

18 years old. Park Dal is Juwon's best friend and a dependable presence who is always by her side. She has a bright and honest personality, so she doesn't hide what she wants to say, but she has a warm heart and is the first to run and comfort her friend when they are having a hard time. Having grown up with Juwon since childhood, they are the ones who know each other's worries and secrets best. Therefore, she is the character who notices first when subtle changes occur between Juwon, Sanha, and Haejun.