The eldest member of the idol girl group 'Luminous' and a confident, head-on center who remains unshaken by crises. Overwhelming Visuals: She is the group's representative 'Center-type' with a glamorous and perfect appearance. Strong Mentality: She possesses a resilient heart that doesn't lose spirit even in the face of malicious comments or trials. Unexpected Charm: While she appears to be a cold beauty on the outside, she is deeper and more dependable than anyone else on the inside.

The leader of 'Luminous' and a former perfectionist trainee who overcomes team crises with a strong sense of responsibility. Reliable Leader: She struggles under a heavy sense of responsibility to mediate conflicts among members and keep the team united. Protagonist of Volume 2: As the lead character of the second volume's narrative, her story deals deeply with school violence rumors within the debut group and her concerns about her qualifications as a leader. Songwriting Talent: A perfect idol trainee who also possesses outstanding musical talent, eventually creating and performing self-composed songs with fellow member Taeri.

The protagonist of this work who became a trainee by chance following a friend, but grows passionately toward her dream of singing after realizing the true charm of the stage. Naturally Gifted: Initially lacking desperation, she is scouted by an agency after showing singing skills that move people's hearts at a local contest. Conflict Between Friendship and Competition: She experiences emotional conflict and an awkward relationship with her best friend since age five, Chohee, as they compete for one of the six spots in the debut group at the same agency. Growth-type Character: Due to joining late, she faces misunderstandings and jealousy from other trainees who think she was 'parachuted' in, but she overcomes this through sincere effort and a genuine attitude.

The strongest rap battler in 'Luminous' and the protagonist of the series finale, hiding hidden pain and a deep sense of responsibility behind a tough exterior. Unrivaled Rapper: The undisputed strongest rap battler in the team who has shown outstanding skills since her trainee days. She has an upright personality, capable of bluntly telling a member who is straying, "That's not the right way." Protagonist of Volume 5: The lead character of the final volume. She faces the greatest crisis of her life, torn between an important competition stage for the group's leap forward and the illness of her grandmother, whom she relies on most. Growth Through Solidarity: She used to stick to a method of enduring alone, whipping herself without revealing her inner feelings. However, in the face of unbearable sadness, she learns to honestly reveal her vulnerability to her friends and grows further by learning the power of true friendship and solidarity.

A member of 'Luminous' and the protagonist of Volume 4. As the youngest (maknae) of Luminous, she courageously confesses and overcomes the inferiority complex and appearance obsession she feels while comparing herself to other members. Protagonist of Volume 4: Leading the narrative of the fourth volume, she suffers from a severe inferiority complex, feeling like she is running in place while other members receive attention for their respective talents (acting, songwriting, variety shows, etc.). Appearance Obsession and Pain: Because she likes desserts and is slightly curvier than other members, she feels intimidated by stage outfits made in small sizes. Eventually, she suffers through repeated extreme dieting (binging and purging) and nearly collapses on stage. Deep Friendship with Mina: She is closest to the eldest member, Mina. By honestly sharing her deep-seated inferiority and worries with the members, she creates an opportunity to bond the Luminous team even more tightly.

The CEO of Double L, the entertainment agency that leads the protagonists in 'Luminous: Debuting from Today'. Sincere Mentor: A cool-headed but warm adult who listens to the members' concerns. Decisive Fixer: She handles problems, such as school violence controversies, strictly according to principle when they arise. Reliable Guardian: She safely protects the members from scandals and realistic crises. She is also the aunt of Park Mina, the center of Luminous.