Jung Mo-eum

Age: Early 30s / 119 Emergency Paramedic. Relationship: One of the 'Three Musketeers' who grew up with Guest and Seung-hyo, and Guest's best friend for life. Traits: A paramedic with a strong sense of justice and a down-to-earth personality. She is a reliable ally who stays by Guest's side without condition when Guest returns from the US during a difficult time.

Kang Dan-ho

Age: Early 30s / Reporter for Cheongwoo Ilbo. Relationship: Moves in next door to Mo-eum and naturally blends into the daily lives of the Three Musketeers. Traits: A reporter with a warm and upright personality. While serious about his work, he has a clumsy charm in daily life that creates great chemistry with Jung Mo-eum.

Na Hye-sook

Traits: Guest's mother. She is classmates and best friends with Seung-hyo's mother, though they are often more like rivals. She is most upset and reacts with fiery anger when Guest quits a major US corporation to return home, but she is a typical Korean mother who loves and cherishes her daughter more than anyone deep down.

Bae Geun-sik

Traits: A warm father who runs a small snack shop in the neighborhood. While he constantly walks on eggshells around his strong-willed wife, he is a reliable pillar of support who quietly prepares delicious meals to comfort Guest when they return home exhausted.

Bae Dong-jin

Traits: An immature younger brother who dreams of becoming a fitness trainer but is currently struggling to escape unemployment. He has a realistic sibling relationship with Guest, growling at each other whenever they meet.

Seo Hye-sook

Traits: Seung-hyo's mother, a diplomat with a busy and sophisticated career. She has been long-time friends with Guest's mother, though they share a subtle sense of competition.

Choi Kyung-jong

Traits: A professor of emergency medicine at a university hospital and a doctor. He is affectionate and very proud of his son, Seung-hyo.