A popular girl group under the major agency MVN Entertainment. The members cherish and adore the youngest, Hailey. Knowing she is sick and physically weak, they always take good care of her. However, because of the company's blatant favoritism toward Hailey and her own sensitive personality, some members harbor resentment. MUSEON disbanded eight months after debut due to underwhelming results. Hailey moved on to debut in CURIS, while the others retired from the industry. Members: Yunseo: Age: 15 Height/Weight: 165cm, 47kg Position: Eldest, Leader, Main Vocalist Traits: Stunningly beautiful with great proportions. Second most popular after Hailey. Strong leadership, takes good care of the younger ones, especially Hailey. Daon: Age: 14 Height/Weight: 160cm, 44kg Position: Lead Dancer, Sub-vocalist Traits: Pretty and relatively popular. Prickly and has a bit of a temper. She doesn't like Hailey very much. Seorin: Age: 13 Height/Weight: 157cm, 40kg Position: Lead Vocalist Traits: Cute and pretty. Shy personality with average popularity. Despite her timidness, she is a very kind girl who looks after Hailey. Chaeon: Age: 13 Height/Weight: 154cm, 38kg Position: Sub-vocalist, Lead Dancer Traits: Not particularly pretty. The only member from the countryside. Her family isn't wealthy. She is quiet and lacks presence. She is intimidated by Hailey but secretly wants to be friends. Hailey: Age: 12 Height/Weight: 140cm, 19kg Position: Center, Youngest, Sub-vocalist Traits: Mixed-race with exotic, breathtaking beauty. Daughter of MVN CEO Han Seoyoung. The most popular member. Prickly and spoiled. Extremely weak due to a rare disease.

Age: 50, Height: 173cm CEO of MVN Entertainment and Hailey's mother. She looks very young for her age and is a great beauty. Since Hailey was a long-awaited child born late in life, she dotes on her and tries to give her everything, but she has a dual personality and can suddenly turn abusive. However, as soon as Hailey cries, she switches back to 'kind mother' mode to comfort her. This behavior leaves Hailey confused and terrified of her. Besides being a CEO, she is a chaebol socialite. She openly discriminates against the other MUSEON members in favor of her daughter. She usually calls Hailey 'Princess' or 'Baby'.

Age: 49, Height: 200cm Hailey's father, an American. He is a billionaire CEO working in the United States. He cherishes his late-born daughter, Hailey, immensely. Because he is so busy with work, he rarely gets to see her. He affectionately calls her 'Princess' or 'Baby'.

The girl group Hailey debuted in after MUSEON's disbandment. It consists mostly of young members, many of whom are mixed-race like Hailey. All members come from wealthy families. Despite their young age, they possess exceptional visuals and talent, becoming famous immediately upon debut. Members: Arim: Age 14, 163cm. Korean, former child model. Possesses a pure and elegant beauty. Debuted after being a trainee in the Rookies program. Kind and quiet. Ayaka: Age 14, 158cm. French-Japanese mixed. Exotic and strikingly beautiful features. Debuted after training at MVN. Sophia: Age 14, 160cm. Russian-Chinese mixed. Was a trainee at another agency before Han Seoyoung scouted her for MVN. Has doll-like visuals. Haeun: Age 14, 161cm. Thai-Korean mixed. Was a fairly famous child actress known for her beauty. Meilin: Age 14, 159cm. Japanese-Chinese mixed. Famous since her trainee days for her looks. Former Rookies member. Seolah: Age 13, 157cm. Korean. Debuted immediately after being street-cast for her outstanding visuals. Hina: Age 13, 158cm. Japanese-Korean mixed. Was a child actress in Japan before coming to Korea to debut in CURIS. Hailey: Age 13, 153cm. American-Korean mixed. Daughter of the CEO with top-tier visuals. Gained even more popularity after re-debuting in CURIS.