Sumin STAYC: The Untold Story Behind Her K-pop Journey

Sumin STAYC stands as a pioneering figure in K-pop leadership, initially serving as the first leader of the six-member South Korean girl group before they introduced an innovative rotation system in August 2023. Born on March 13, 2001, in Pohang, North Gyeongsang, this 24-year-old idol dedicated over five years to training before finally making her debut with STAYC on November 12, 2020.

Behind her public persona as a STAYC member, Bae Sumin brings unique qualities to the group's dynamic profile. Despite being the shortest member at 159 cm (5'3"), her influence within the STAYC kpop landscape remains significant. Before joining High Up Entertainment in 2018, she trained at Plan A Entertainment, building the foundation for her Sumin kpop journey. Additionally, she hosts "Sumin's STAYZ" on KBS CoolFM and lives by the thoughtful motto: "Don't look at the trees, look at the forest." 

Early Life and First Steps Toward K-pop

Bae Sumin's story begins in the coastal city of Pohang, North Gyeongsang, South Korea, where her journey toward becoming a K-pop idol took root long before she stood on stage as a STAYC member.

Growing up in Pohang

Born as the second of two daughters, Sumin's childhood was spent in the industrial port city of Pohang. Her educational path took her through Pohang Idong Elementary School and Pohang Idong Middle School before she graduated from Kyungil High School.

During her formative years, Sumin would often find herself captivated by Girls' Generation music videos playing on television screens in local supermarkets. These chance encounters sparked something in the young girl, who would spontaneously dance along to the choreography. Although she developed an early interest in performing, Sumin's talents initially leaned more academic than artistic. By her own admission, she possessed "all the body skills" but was "tone deaf" in her younger years, and "was better at studying than singing".

Her unexpected audition story

Sumin's path to stardom came through an entirely unexpected channel. A talent scout from a rookie development team discovered her after seeing her photograph and made the journey specifically to Pohang to meet her. What followed was far from the traditional audition setting—Sumin's first audition took place in a karaoke bar, an unorthodox beginning to what would become a remarkable career.

Years later, her pre-debut appearances included a surprising cameo in a 2016 BTS Puma commercial, where she played a schoolgirl whose lollipop was taken by RM. Remarkably, she only learned about the filming opportunity the day before shooting. As she recalled, "I didn't know what kind of filming it was, and I remember being like, 'Really?' and went filming". This serendipitous encounter held special meaning, as she would later name BTS as her role models due to their exceptional teamwork.

Furthermore, Sumin appeared in VICTON's reality show "Me & 7 Men" as "the invisible girl", gaining valuable on-camera experience before her official debut.

Initial dreams and doubts

Contrary to many idols who dream of stardom from childhood, Sumin had different aspirations. "I actually didn't really want to be a singer at the time," she confessed about her initial casting. Her academic abilities had her considering more conventional career paths—if not for her K-pop journey, Sumin believes she would have become an office worker while running a cooking and mukbang YouTube channel on the side.

Her dedication to academics made the decision to pursue entertainment particularly poignant. "She was eager to study," but ultimately made the difficult choice to "give up and come to Seoul to become a trainee". This sacrifice marked the beginning of her professional journey, starting at Plan A Entertainment before she transferred to High Up Entertainment in 2018.

Interestingly, Sumin's path crossed with future STAYC member Seeun even before they officially trained together. Upon recognizing Seeun, who was "well-known for her pretty looks" at their school, Sumin approached her agency's casting director about the beautiful girl—only to learn Seeun had already passed her audition and would soon join as a trainee. This coincidence seemed to foreshadow their future as groupmates, with Sumin recalling her reaction: "This is so cool".

Training Years: The Foundation of Sumin’s Skills

The half-decade of rigorous training shaped Sumin into the multifaceted performer who would ultimately lead STAYC. Her journey through two different entertainment companies provided her with diverse experiences that contributed to her comprehensive skill set.

Joining Plan A Entertainment

Sumin's professional training journey began at Plan A Entertainment, a company known for producing groups like Apink and VICTON. Her initial years as a trainee introduced her to the demanding world of idol preparation, where she faced the challenge of improving her self-described "tone deaf" singing abilities. Throughout this period, she devoted herself to mastering the fundamentals of K-pop performance.

At Plan A, Sumin had some memorable experiences, including crossing paths with other trainees who would later debut in different groups. Notably, she appeared in VICTON's pre-debut reality show "Me & 7 Men" as "the invisible girl," gaining valuable camera experience that would serve her well in the future.

Switching to High Up Entertainment

In 2018, Sumin made a pivotal career move by transferring to High Up Entertainment, a newly established company founded by legendary producer duo Black Eyed Pilseung. This decision proved crucial in her development as an artist. High Up Entertainment offered something unique compared to other agencies – direct mentorship from producers who had created numerous hit songs for established K-pop acts.

Under Black Eyed Pilseung's guidance, Sumin received specialized training focused on developing her distinctive voice color and performance style. The company's founder, Jeon Goon, took a personal interest in cultivating each trainee's natural strengths rather than forcing them into predetermined molds.

What 5+ years of training taught her

The extensive training period equipped Sumin with more than just technical skills. By the time of her debut, she had developed:

Vocal versatility: From being initially "tone deaf," she transformed into a vocalist with a distinctive tone that complements STAYC's signature sound
Leadership capabilities: Her natural sense of responsibility and longest training period among members prepared her for her eventual role as STAYC's first leader
Performance stability: Years of practice gave her confidence and consistency in live performances

One of the most significant lessons from her training period was perseverance through uncertainty. "I thought I was going to debut several times, but it kept getting cancelled," Sumin once revealed, highlighting the emotional rollercoaster trainees often experience.

Beyond technical abilities, Sumin developed emotional resilience. The competitive training environment taught her to balance healthy ambition with teamwork, a quality that would later define her leadership style in STAYC. She learned to navigate the delicate balance between pushing herself and supporting others.

Moreover, Sumin's training years fostered her attention to detail. As one of the longest-training members, she gained an eye for the subtle elements that elevate performances. This meticulous approach influenced how she would later mentor newer members, emphasizing both technical precision and authentic expression.

The culmination of these years was evident when Sumin finally stepped onto the stage as a STAYC member. Her journey from a self-described "tone deaf" student to a poised idol exemplifies how the demanding K-pop training system can transform raw potential into polished talent when combined with unwavering determination.

Debut with STAYC: A New Chapter Begins

After years of preparation, Sumin's debut moment finally arrived in autumn 2020 when High Up Entertainment began revealing the members of their first-ever girl group. The announcement marked the beginning of Sumin's official journey as an idol after her extensive training period.

Being the second member revealed

On September 9, 2020, High Up Entertainment officially introduced Bae Sumin as the second member of their upcoming girl group. This strategic positioning highlighted her importance to the group's foundation. The member unveiling process followed a deliberate schedule, with Sieun announced first, followed by Sumin and Seeun.

The complete lineup was gradually revealed through prologue films released between October 12-14, with the members unveiled in pairs: Sieun and Isa, Seeun and J, and finally Sumin and Yoon. This methodical introduction built anticipation among K-pop fans curious about the new group from Black Eyed Pilseung's company.

Throughout the pre-debut period, Sumin participated in promotional activities through 1theK's YouTube channel. These included dance covers of established groups like Blackpink, BTS, and Stray Kids, which garnered over 1 million views, alongside vocal covers of Twice and Red Velvet songs that accumulated more than 2 million views. These pre-debut showcases allowed audiences to glimpse Sumin's performance abilities before her official debut.

Debut with 'Star To A Young Culture'

On October 12, 2020, the group's name was officially announced as STAYC—an acronym for "Star To A Young Culture". Subsequently, on October 22, the title of their debut single album was confirmed to share this name, with "So Bad" selected as the lead single.

The debut project carried significant industry weight as it was produced by Black Eyed Pilseung, the acclaimed producing duo known for creating hit songs like "TT," "Touch My Body," "Roller Coaster," and "Dumhdurum". The producers described STAYC's sound as "Teen Fresh," a fusion of "Teen" and "Fresh" that emphasized the group's "unique individual vocal colors".

Sumin STAYC and her groupmates officially debuted on November 12, 2020, with the release of their single album "Star To A Young Culture". The project contained two tracks: the title song "So Bad" and the B-side "Like This". Following the album release, STAYC promoted through a V Live debut showcase and made their music show debut on November 13, 2020, at KBS Music Bank. This was followed by appearances on Show Champion, Inkigayo, and The Show.

Initial public reactions to Sumin

The debut achieved impressive results, especially considering STAYC launched under a relatively new agency without major label backing. The "So Bad" music video received over 2.6 million views within its first 24 hours, demonstrating strong initial interest in the new group.

The album sold over 4,300 copies on its first day—the highest first-day sales for any debut girl group in 2020. Within its first week, sales exceeded 10,000 copies, making it the first debut album by a girl group in 2020 to reach this milestone. On the charts, the album initially debuted at number 17 on the weekly Gaon Album Chart before eventually peaking at number 6.

As for Sumin specifically, her position as one of the earliest revealed members and her performance as the group's first leader helped establish her presence within the K-pop landscape. Fifty days after their debut, on December 31, 2020, STAYC announced their official fan club name "SWITH"—a combination of STAYC and "WITH," meaning "together with STAYC" or "I'll be by STAYC's side".

While their debut was successful, STAYC's true breakout moment came early in 2021 with their viral hit "ASAP," which further solidified the group's position in the competitive K-pop industry. This foundation laid during their debut period provided Sumin and STAYC the platform from which they would continue to evolve their musical identity in the years to come.

Leadership Journey: From Eldest to Guiding Force

Beyond her status as one of STAYC's main vocalists, Bae Sumin carved out a significant place in the group's history through her pioneering leadership role. Her journey exemplifies how leadership in K-pop continues to evolve, with groups experimenting with new approaches to team dynamics.

Her role as the first leader

From STAYC's debut on November 12, 2020, Sumin served as the group's inaugural leader. As the eldest member, this position aligned with K-pop's traditional leadership structure where the oldest member often assumes the guiding role. Throughout this period, she shouldered responsibilities that included mediating between members and management, representing the group in interviews, and guiding their public image.

Throughout STAYC's early releases—from "So Bad" to "Beautiful Monster"—Sumin maintained her leadership position, helping establish the group's "Teen Fresh" concept and guiding their rapid rise in popularity. Her leadership coincided with some of STAYC's breakthrough moments, including their viral hit "ASAP" and the success of tracks like "Stereotype."

Why STAYC chose rotating leadership

In a surprising development, STAYC announced through a Weverse Live on April 1, 2023, that they would implement a new rotational leadership system. Under this innovative approach, different members would take turns serving as leaders for each comeback period. This announcement initially confused fans, as it came on April Fool's Day, leading many to question whether it was a joke.

However, Sumin confirmed the leadership change through her personal bubble message that same day, noting it was indeed a company decision. Following Sumin's term, Sieun and Seeun stepped in as co-leaders beginning April 2, 2023, though some sources indicate the official handover was finalized in August 2023.

This rotating system represents an innovative approach to group leadership in K-pop, allowing multiple members to develop leadership skills while potentially reducing the pressure on any single individual. It also reflects the group's collective desire to showcase different strengths and perspectives.

How Sumin shaped group dynamics

Sumin's impact on STAYC's identity remains evident even after her official leadership term concluded. During interviews for their 2024 studio album "Metamorphic," she spoke about the group's transformation: "We wanted a complete transformation—so bold that people wouldn't recognize us. That was more thrilling". This statement illuminates how her vision continued to influence the group's artistic direction.

Her leadership style appears to have emphasized teamwork and authentic expression. As she revealed in an interview about her admiration for BTS, Sumin values "how good their teamwork is, not just with each other but also with their staff". This philosophy seemingly guided her approach to leading STAYC, creating an environment where each member could contribute their unique strengths.

The impact of this leadership foundation became apparent in July 2024 when member Sieun remarked, "People have always seen us in a certain way, but now we want to present our true selves, without being framed by others". This evolution toward more authentic self-expression suggests Sumin established a foundation that allowed the group to grow confidently into their artistic identities.

Sumin’s Artistic Identity: Voice, Rap, and Dance

What sets Bae Sumin apart within the competitive K-pop landscape is her distinctive triple-threat status as a vocalist, rapper, and dancer. Each performance element contributes to her multifaceted artistic identity within STAYC.

Her vocal tone and live performance skills

Sumin's vocal color adds a unique dimension to STAYC's signature sound. Her melodic tone sits between warm and bright, providing versatility across different song styles. Throughout STAYC's discography, she consistently demonstrates stable live performances, maintaining pitch accuracy even during complex choreography.

In the group's vocal dynamics, Sumin often handles supporting verses and harmonies that build the songs' foundations. Her voice particularly shines in mid-tempo tracks where her natural timbre can fully express emotional nuances. Nonetheless, she's demonstrated remarkable growth since debut, expanding her range and vocal techniques.

A standout aspect of Sumin's performances is her unwavering stability—rarely missing notes during live shows despite STAYC's commitment to singing live. This reliability makes her an anchor for the group's overall sound quality.

Rap style and stage presence

As a rapper, Sumin adopts a straightforward, clean delivery style that prioritizes clarity over speed. Her approach is characterized by crisp enunciation and steady rhythm, complementing the group's "Teen Fresh" concept perfectly. Unlike rappers who focus on technical complexity, she emphasizes conveying the lyrics' meaning through expressive delivery.

On stage, Sumin projects confidence without overshadowing her groupmates. Her facial expressions remain consistently engaging, maintaining the group's energetic performance standard. Furthermore, she transitions seamlessly between vocal and rap sections, demonstrating versatility that enhances STAYC's performance cohesion.

Dance strengths and fan praise

Despite being one of the shorter members of STAYC at 159cm, Sumin executes choreography with remarkable precision. Her dance style emphasizes clean lines and synchronized movements rather than power or flamboyance. Consequently, she maintains formation accuracy and timing that contributes significantly to the group's polished performances.

Fans frequently praise Sumin's attention to detail in dance, noting how she maintains consistent energy throughout performances. Her movements appear effortless yet precise—a testament to years of training. Additionally, she exhibits particular strength in point choreography that highlights facial expressions alongside physical movements.

Overall, Sumin's artistic identity within STAYC balances technical proficiency with authentic expression. Her triple-threat capabilities allow her to seamlessly transition between singing, rapping, and dancing, establishing her as an integral component of STAYC's performance chemistry.

Personality and Relationships Within STAYC

Within the STAYC dormitory walls, Bae Sumin reveals a personality that balances leadership with youthful charm—a contrast to her composed public image. Her interactions with fellow members showcase the authentic dynamics that have cemented STAYC's reputation for genuine chemistry.

Roommate stories and member chemistry

Throughout STAYC's journey, dormitory arrangements have evolved significantly. Initially, Sumin shared a room with Yoon before the group's housing upgrade. According to Sumin herself, their morning routine featured a humorous pattern: "When she wakes up in the morning, she shouts 'Simjayun!' and repeats going back to sleep." Sumin would awaken to Yoon's alarm, yet ironically found herself nudging the sleepy Yoon awake.

Following their dorm upgrade in 2021, roommate pairings shifted, with Sumin moving in with Sieun while Yoon roomed with J. This rearrangement reflected Sumin's nurturing nature, as she explained on "Kim Shin Young's Noon Song of Hope" radio show: "I let them use the bigger room so that they can use the restroom comfortably" since Yoon and J were still attending school. Most recently, as their success has grown, STAYC members reportedly upgraded to having individual rooms.

Her playful vs. serious sides

Despite being the eldest member, Sumin is frequently mistaken for the youngest due to her petite stature and youthful expressions. Fellow members unanimously voted her as both "the cutest" and "the biggest prankster" in the group. In Elle magazine's interview, when asked who makes the group laugh most, Sumin received votes from J: "These days, it's J. She does things that crack me up and has these funny expressions".

Nevertheless, Sumin demonstrates remarkable duality. Her playful disposition transforms into calm authority during critical moments. As noted by fans: "When he is serious, he definitely shows his leader-like side... in the practice video, unlike usual, he showed charismatic leadership throughout the practice, causing a reaction among fans saying, 'This is why you are the leader'".

Her MBTI personality type—ISFJ "Defender"—aligns perfectly with this duality. This personality type is characterized by being "warm and unassuming" while reliably meeting deadlines and upholding traditions, often "operating behind the scenes".

Nicknames and what they reveal

Sumin's collection of nicknames reflects her multifaceted personality. Her most common nickname "숨" (Sum) originated simply from saying "Sumin" quickly. This evolved into variations like "BaeSum," combining her surname with her nickname.

More creatively, members call her "Tonyangyi" (토냥이), acknowledging her facial resemblance to both rabbits and cats. She frequently emphasizes this rabbit-like quality during broadcasts. Another nickname, "Jasmine," emerged from international appearances, with members noting "Whenever the members mention Jasmine, they always say 'Jasmine? I got the nickname 'Bae Soo-min'".

Perhaps most telling is her nickname "colored glasses," which celebrates her consistently stable live performances—a testament to both her professionalism and reliability. This balance of playfulness and dependability continues to define Sumin's place within STAYC's dynamic.

Solo Activities and Fan Engagement

Beyond her group activities with STAYC, Bae Sumin has cultivated a distinctive individual presence through various solo endeavors that showcase her versatility and strengthen her connection with fans.

Hosting STAYZ radio

In late 2021, Sumin STAYC expanded her artistic horizons by stepping into broadcasting. High Up Entertainment announced on December 30 that she would host KBS Cool FM's "Station Z" radio program every Monday for five weeks starting January 3, 2022. Using the DJ nickname "SsumD," Sumin led a show specifically designed for the MZ generation, creating a space for "friendly and honest conversations" with listeners.

The radio program featured a special format where fellow STAYC members appeared as weekly guests to support Sumin and enrich the broadcast with their "bright energy". The first episode welcomed Seeun as a guest, demonstrating their "perfect chemistry" on air. Impressively, the show was made available across multiple platforms including KBS CoolFM (89.1 MHz), MyK, and the "Station Z" YouTube channel.

Vlogs and behind-the-scenes content

Sumin regularly creates personal content that gives fans glimpses into her world. Her YouTube vlogs, particularly her "전지적 천장 시점" (Omniscient Ceiling Perspective) series, offer unique behind-the-scenes footage of STAYC's activities. These videos showcase her creativity and witty personality through an unconventional ceiling-view filming style.

Plus, she shares candid moments from music video productions. During filming for "RUN2U," Sumin revealed her struggles with running scenes—a challenge she had previously faced while shooting "STEREOTYPE" when directors noted her arms had been "too low while running". These honest revelations about filming difficulties make her relatable to fans.

How she connects with SWITH

Sumin's dedication to STAYC's fandom (SWITH) extends beyond digital content. In May 2023, she participated in STAYC's second fan meeting, "SWITH Gelato Factory," where all tickets sold out immediately after sales opened on April 15. This three-day event at Seoul's Yes24 Live Hall included talks, games, and interactive activities where Sumin connected directly with fans.

Her approach to fan engagement reflects authenticity—from sharing her vinyl record collection that includes Shawn Mendes and Day6 albums to revealing personal details like owning four cats named Biji, Dubu, Angkko, and Kongi. First and foremost, these genuine interactions have established Sumin as one of K-pop's most accessible idols despite her growing fame.

Visual Evolution and Public Image

Bae Sumin's visual presentation has undergone remarkable transformations throughout her STAYC journey, reflecting both artistic growth and personal evolution. Her changing looks have become a visual diary of the group's conceptual development.

Hair transformations and styling

Throughout her career, Sumin's hair has served as her most distinctive style signature. During STAYC's debut with "SO BAD," she briefly appeared with striking pink hair before switching to a sophisticated two-tone beige and black style for promotional activities. For "STAYDOM" promotions, she experimented with purple hair before refreshing her image by cutting bangs—a change that markedly enhanced her already cute appearance.

"STEREOTYPE" era showcased Sumin's versatility through diverse styling including pigtails, half-up arrangements, and sleek straight hair that garnered substantial fan praise. Correspondingly, her return to pink hair during "Teddy Bear" activities triggered "explosive" fan reactions, with many noting she had "renewed" her image. Most recently, for STAYC's 2025 "S" album, Sumin studied Rihanna's performances to embody a bolder visual concept.

Her 'cute but leader' duality

Notwithstanding her position as STAYC's eldest member, Sumin is frequently mistaken for the youngest due to her petite frame and youthful expressions. This misconception is amplified by what fans describe as her "secret sense of silliness" and tendency to be playfully teased by younger members.

Henceforth, this cute exterior contrasts dramatically with her leadership capabilities. During practice sessions, Sumin demonstrates a charismatic authority that prompts fan comments like "This is why you are the leader". Additionally, STAYC members have humorously exposed Sumin as the group's primary prankster, with Sieun revealing she "lies a lot" with "ridiculous lies that make no sense".

How fans perceive her today

In 2025, Sumin deliberately challenged her established image. "I wanted to break the strong bright and cute image with this song. I think I found a new me through style changes and research," she confessed about STAYC's mature concept shift. This transformation represented her evolution "from a caterpillar to a butterfly".

Fans now recognize Sumin's visual identity as that of a "small and precious fairy-dol" while appreciating her willingness to embrace bolder concepts. The dramatic shift from "teen fresh" to more mature styling showcases her artistic versatility and determination to grow beyond comfortable boundaries.