The Real Seoi: Behind-The-Scenes Look at H1-KEY's Talented Performer

Seoi stands out as the eldest member of South Korean girl group H1-KEY, despite ironically earning the nickname "Boss Baby" for her youthful appearance. Born as Lee Ye-jin on February 12, 2000, in Seongnam, Gyeonggi-do, South Korea, she embarked on her K-pop journey after training for three years before finally making her debut.

After being revealed as the second member of GLG's first girl group in November 2021, Seoi officially debuted with H1-KEY on January 5, 2022, through their first single album 'ATHLETIC GIRL'. Additionally, she balances her performing career with her studies at Dongduk Women's University, where she's enrolled in the Broadcasting and Entertainment Department. Although she appears confident on stage, Seoi actually suffers from acrophobia and cannot ride amusement rides. Furthermore, her positive outlook is evident in her life motto: "Seeing the bright side will brighten up my life", which perfectly reflects her approach to both her personal life and professional career as a rising K-pop performer.

Early Life and Background

Born in the city of Seongnam in Gyeonggi Province, South Korea, Seoi grew up in a close-knit family with her parents and a younger brother who was born in 2010. Her birth name, Lee Ye-jin, would later give way to her stage name as she pursued her dreams in the entertainment industry.

Birthplace and family

Seoi's upbringing in Seongnam provided her with a stable foundation that would later support her journey into the competitive world of K-pop. Though she doesn't frequently discuss her family dynamics in public, her family has been supportive of her career choices. Her mother, in particular, played a pivotal role in her decision to become an idol, as they often watched performances together.

Education and school activities

Unlike many idols who missed out on typical school experiences due to training, Seoi thoroughly embraced her educational journey. "I really liked school!" she once shared in an interview, expressing how she enjoyed everything from wearing her school uniform to participating in various activities. Her academic path took her through Anmal Elementary School and Songrim Middle School before she graduated from Seohyun High School.

What truly sets Seoi apart is her active involvement in school life. Throughout her middle school and high school years, she was consistently part of the student council. Interestingly, during her middle school days, she formed a theater club and served as its general manager, showcasing her leadership qualities from an early age.

Her favorite school subjects included English, Science, and IT, reflecting her diverse academic interests. Presently, she continues her education at Dongduk Women's University, where she's enrolled in the Broadcasting Entertainment program, balancing her academic pursuits with her professional career.

First interest in music and performance

The spark that ignited Seoi's passion for performing came from an unexpected moment shared with her mother. While watching television together, they saw Girls' Generation (SNSD) performing their hit song "Gee". This performance left a profound impression on young Seoi.

"She saw how happy they were while performing and felt like she wanted to do that too," according to sources close to the idol. This defining moment set her on the path toward becoming a performer herself. The joy and energy displayed by SNSD members resonated with her, planting the seed for what would eventually grow into her career with H1-KEY.

Her journey from that inspirational moment to becoming an idol wasn't immediate or straightforward, nonetheless. Before her debut, Seoi underwent three years of rigorous training, including time at YG Entertainment. As she later described in an interview, the training period taught her about "the 'real world', life and society". She also experienced the emotional challenge of watching friends drop out of the training process, which she described as painful yet formative.

Trainee Journey Before H1-KEY

Seoi's path to stardom began with her acceptance into one of South Korea's most prestigious entertainment companies. Her trainee period offered valuable lessons that shaped her not just as a performer, but as a person navigating the competitive world of K-pop.

Training under YG Entertainment

Following her inspiration from SNSD's "Gee" performance, Seoi pursued her dream by joining YG Entertainment's rigorous training program. She became part of YG Trainee Team 2, where she honed her skills alongside other aspiring idols who would subsequently find success elsewhere. Notably, she trained with PURPLE KISS's Chaein and Billlie's Moon Sua during this period, forming connections that lasted beyond her time at the company.

For approximately three years, Seoi dedicated herself to the demanding YG training regimen. This significant investment of time demonstrates her commitment to perfecting her craft prior to debut. As part of Team B within YG's trainee structure, she worked alongside other notable trainees including Purple Kiss' Ireh, creating a foundation of skills that would ultimately benefit her future career.

Challenges faced during training

The K-pop training system is notoriously demanding, often requiring trainees to practice singing and dancing for twelve to fifteen hours daily. For Seoi, the emotional toll proved especially challenging. In her own words, "It was particularly painful to watch friends drop out of the gruelling training process one by one".

This difficult experience provided profound life lessons. As she reflected in an interview, "I started to learn about the 'real world', life and society in a way. There were a lot of fun moments, but there was likewise a lot of getting hurt, learning and maturing". These insights reveal how the training process served as more than just performance preparation—it became a formative life experience.

K-pop training programs typically impose strict regulations, including:

Isolated meals for male and female trainees
No-dating policies
Limited access to personal phones
Severe diet plans with prohibited foods
Weekly weight checks posted publicly

Seoi navigated these challenges for years, demonstrating remarkable resilience in an environment where many trainees ultimately abandon their dreams.

Transition to GLG and selection for H1-KEY

Her journey took an unexpected turn when GLG (Grandline Group) discovered her talent. As she explained, "I trained under YG for three years but one day got casted by GLG company and became the first member of H1-KEY". This opportunity arrived at the perfect moment, providing a path forward after her substantial training period.

On November 26, 2021, Seoi was officially introduced as H1-KEY's second member, even though she had been the first trainee selected for the group. This marked the beginning of a new chapter in her career. The group's official social media accounts had opened just days earlier on November 20, signaling the start of their pre-debut promotions.

GLG, a newly-established sub-label of the now-defunct hip-hop based label Grandline Entertainment, had announced plans to debut their new girl group on January 5, 2022. Seoi would soon find herself at the forefront of this exciting new venture, applying all she had learned during her years of training to her long-awaited debut.

Effectively, her transition from YG trainee to H1-KEY member represented the culmination of years of dedication, perseverance through challenges, and the patience to wait for the right opportunity to showcase her talents on a larger stage.

Debut and Rise with H1-KEY

After years of preparation, Seoi's dream finally materialized when she stepped onto the K-pop stage as part of H1-KEY, marking the beginning of a remarkable journey from trainee to established performer.

Debut with 'Athletic Girl'

H1-KEY made their official entry into the K-pop scene on January 5, 2022, with their debut single album "ATHLETIC GIRL". The group held a press showcase on the same day, introducing themselves to the media and fans. Seoi, alongside original members Riina, Yel, and Sitala, made their broadcast debut just two days later on January 7, appearing on KBS2's "Music Bank".

Their debut proved impressively successful for a rookie group from a smaller company. The music video for "Athletic Girl" surpassed 10 million views on YouTube in just over two weeks after its release. Moreover, the song topped the iTunes Top K-Pop Songs Chart in nine regions, including Turkey, Vietnam, Australia, the UK, Canada, Indonesia, Taiwan, and the United States. This initial success established a solid foundation for their future endeavors.

Comebacks and key performances

Following their debut, H1-KEY continued to build their discography with meaningful releases:

On July 6, 2022, they released their first maxi single album "RUN" with a significant lineup change - new member Hwiseo joined the group, replacing former member Sitala.
On January 5, 2023, exactly one year after their debut, they returned with their first mini album "Rose Blossom" featuring the title track "건물 사이에 피어난 장미 (Rose Blossom)".
On August 30, 2023, they released their second mini album "Seoul Dreaming" with the title track "SEOUL (Such a Beautiful City)".
In 2023, members Riina and Hwiseo participated in the Mnet survival show "Queendom Puzzle".
On September 5, 2023, H1-KEY achieved a significant milestone by securing their first music show win on "The Show".
They continued their momentum with their third EP "Love or Hate" on June 19, 2024.
Most recently, on June 26, 2025, the group released their fourth mini album "Lovestruck".

Throughout these comebacks, Seoi has consistently delivered powerful performances, contributing to the group's growing popularity. Their musical direction has shown thoughtful evolution, initially focusing on physical health themes with "Athletic Girl" and "Run," then shifting toward mental health concepts with releases like "Rose Blossom" and "Seoul".

Her role as the group leader

As H1-KEY's leader, Seoi brings a calm and charismatic presence to the group. Her leadership style reflects the same organizational skills she demonstrated in school, where she was part of the student council and even formed and managed a theater club [previous sections].

In the group's messaging, Seoi often takes the lead in articulating their vision. For their "Seoul Dreaming" comeback, she expressed: "With this album, Seoul Dreaming, we wanted to deliver a positive message of: 'Those of you who are chasing your dreams are beautiful and precious, and therefore we shall never give up and keep chasing our dreams!'".

Her leadership extends to their performance approach as well. She emphasizes authenticity, stating, "I believe we all have different charms. So, expressing our own personality & charisma helps us to blend in as H1-KEY and it is the most significant charm of us as a team. So we try to show our true selves".

Seoi's commitment to growth is evident in her dedication to developing her skills beyond performing. In a recent interview about their "Lovestruck" album, she expressed interest in production, saying, "While I have personal favorites like R&B and hip-hop, I'd love to produce a song that suits our team". This showcases her evolving vision for H1-KEY's musical direction and her dedication to their continued success.

Personality and MBTI Evolution

Understanding the evolving personality of Seoi provides deeper insight into what makes her a distinctive figure within H1-KEY and the broader K-pop landscape.

From ESFJ to ESTJ

Seoi's personality profile has undergone an intriguing evolution since her debut. Originally identifying as an ESFJ personality type, she has since transitioned to ESTJ. This shift reflects her growth as both an artist and leader. ESFJs are typically characterized as caring, social individuals with a natural talent for building strong connections, always eager to help others. Conversely, ESTJs excel as administrators who manage people and tasks effectively, bringing structure and organization to situations.

Such personality shifts often occur during significant life transitions or periods of growth. Indeed, the demanding nature of debuting and leading a K-pop group likely influenced this evolution in Seoi's personality. As one personality expert notes, "a change in confidence can make it look like one's type has changed", suggesting that Seoi's increased leadership responsibilities may have emphasized her natural administrative qualities.

How her personality shows on and off stage

On stage, Seoi projects a calm, charismatic presence that complements her role as the group's leader. Off stage, however, several distinctive traits emerge. She considers herself a "people person" who leads her group effectively. Her cleanliness obsession manifests in practical ways, such as regularly cleaning her phones and tablets with alcohol spray.

Among her endearing quirks is her habit of freezing suddenly while deep in thought. At night, she unknowingly knocks over dolls and blankets in her dorm room while sleeping. These contrasting behaviors—composed leader by day, unintentionally chaotic sleeper by night—showcase the multifaceted nature of her personality.

Certainly, this duality extends to her public persona as well. Behind her composed exterior lies what her groupmate Hwiseo describes as "unexpected playful, and somehow goofy charms" that surprise fans who see her in various content. This reveals how Seoi maintains different facets of her personality, adapting between her responsibilities as a leader and her natural playfulness.

Group members' views on her character

Her fellow H1-KEY members offer unique perspectives on Seoi's character. Yel describes her style as simultaneously "hip and lovely" while also characterizing her as both "timid but easy-going" and "quiet but active". These seemingly contradictory descriptions highlight the complexity of Seoi's personality.

The youngest member, Yel, additionally mentions that "Seoi really takes care of me well," pointing to her nurturing side that becomes evident in behind-the-scenes content like their baking video. Furthermore, according to Riina, Seoi "laughs easily at jokes", revealing her receptiveness to humor despite her sometimes reserved demeanor.

Throughout group interactions, Seoi's ESTJ qualities become apparent in how she organizes activities and supports other members, yet she balances this administrative side with genuine warmth and playfulness that endears her to both groupmates and fans alike.

Hobbies, Habits, and Daily Life

Beyond her professional life as H1-KEY's leader, Seoi enjoys simple pleasures that reveal her multifaceted personality. Her off-stage interests and quirky habits provide fans with glimpses into the real person behind the polished performer.

Baking and collecting pretty things

In her spare time, Seoi finds joy in baking delicious treats for those around her. This hobby reveals her nurturing side, as she particularly delights in sharing her baked goods with friends and watching their positive reactions. Interestingly, her baking hobby aligns perfectly with her organized ESTJ personality traits, given the precision required for successful recipes.

Alongside baking, Seoi has developed a passion for collecting beautiful items. This aesthetic appreciation manifests throughout her personal spaces and style choices. Fans have noticed this collector's mindset extends to her fashion sensibilities, where she often incorporates visually appealing elements into her outfits.

Cleanliness obsession and tech cleaning

One of Seoi's most distinctive traits is her intense focus on cleanliness. This characteristic goes beyond typical tidiness—she meticulously maintains her personal spaces and belongings. Most notably, she regularly disinfects her phones and tablets with alcohol spray, a habit that reflects her attention to detail.

Her technology cleaning practices stand out among her groupmates. Whereas many people might occasionally wipe down screens, Seoi takes electronic device maintenance to another level. This behavior aligns with recommended practices for extending device lifespan, as improper cleaning methods can damage sensitive electronics through scratching or moisture infiltration.

Funny sleep habits and quirks

Remarkably, Seoi's composed daytime demeanor contrasts sharply with her nighttime behavior. According to her dormmates, she unknowingly knocks over dolls and blankets in their bedroom while sleeping. This unconscious habit has become an endearing quirk that her groupmates often tease her about.

Another distinctive trait is her tendency to freeze suddenly when deep in thought. These momentary pauses occur mid-conversation or activity, catching others by surprise. Her groupmate Riina has observed that Seoi "laughs easily at jokes", adding another layer to her personality that fans find endearing.

These daily habits and hobbies create a more complete picture of Seoi as someone who balances her professional responsibilities with personal interests. Her attention to cleanliness, creative outlets, and unconscious quirks all contribute to the charm that has endeared her to H1-KEY fans worldwide.

Friendships and Group Dynamics

The strength of any K-pop group lies in its interpersonal dynamics, and Seoi's relationships within H1-KEY showcase her natural ability to foster meaningful connections.

Bond with Riina, Yel, and Hwiseo

At the core of H1-KEY's success is the genuine bond between its members. As the group leader, Seoi created a foundation for team chemistry through her communication philosophy. "We had a shorter amount of time than others to form a team spirit," she explained, "I emphasized to the girls, let's be ourselves and talk to each other a lot, and I meant it. I shared even the most ridiculously small things, like, 'I was so annoyed today because my zipper got stuck.' Whether it is positive or negative, trivial or serious, we share every emotion".

This approach to open communication has created an environment where members feel comfortable expressing themselves. Yel confirmed this dynamic: "We enjoy playing pranks on each other and watching fun videos together. I think that's where our chemistry has developed. Especially when we watch videos and engage in lively discussions, it feels like we're friends despite the age difference".

Instead of relying solely on their training period for connection, H1-KEY built relationships through intentional interaction. "I don't think more years together necessarily equates to greater teamwork. You could train with someone for years and never talk," Yel reflected, "But we really talk and share a lot with each other, communicate and grow together, and that's what's important".

Close friends outside H1-KEY

Beyond her group relationships, Seoi maintains connections from her training days. Specifically, she is close to PURPLE KISS's Chaein and Billlie's Moon Sua, having trained together at YG Entertainment. These friendships represent important connections in her professional network, linking her to peers who understand the unique challenges of the idol journey.

How she supports her members

Seoi's leadership style emphasizes emotional support alongside professional guidance. For younger members, she serves as both mentor and confidante. "They were my eonni [older girl or sister], and since we live together, they feel like my mom," Yel shared about Seoi and other older members, "I asked them for advice about everything and talked about everything, including my worries. When I reread my diary from my trainee years, I can see how much they patiently listened to me whining".

Through difficulties, Seoi helps maintain group morale. Reflecting on challenging times, she noted, "In a way, it made us stick together even more, appreciate each other. Almost a motivation, if you will". This supportive approach creates a foundation of mutual respect that enhances their performances and public appearances.

Inspirations and Role Models

Every artist's journey is shaped by those who came before them, and Seoi finds inspiration from a diverse array of performers who've influenced her artistic vision and career aspirations.

Why she admires Son Yejin, Hyuna, and Little Mix

Among the influential figures Seoi consistently names as her role models are actress Son Yejin, K-pop soloist Hyuna, and British girl group Little Mix. This eclectic selection reveals her appreciation for different facets of entertainment. Her admiration for Son Yejin points toward Seoi's interest in acting beyond her musical career. Meanwhile, Hyuna represents a bold, charismatic performance style within K-pop that has likely influenced Seoi's own stage presence. Rounding out this trio is Little Mix, suggesting Seoi draws inspiration from international girl groups known for their vocal harmonies and group dynamics.

In interviews, Seoi has repeatedly mentioned these three influences, indicating that they remain constant sources of inspiration throughout her career development. Given that these role models excel in different areas of entertainment, they collectively offer Seoi a well-rounded vision of artistic expression that encompasses acting, solo performance, and group dynamics.

The impact of SNSD's 'Gee' on her dream

Perhaps most significantly, Seoi traces her initial inspiration to become an idol back to a specific moment—watching Girls' Generation (SNSD) perform their iconic hit "Gee" on television with her mother. This pivotal experience clearly demonstrated to young Seoi the joy that performing could bring, as she "saw how happy they were while performing and felt like she wanted to do that too".

Understandably, this moment resonated deeply. "Gee" itself was a landmark release that "played a part in starting it all and paving the way" for K-pop's global expansion. The song's influence extended far beyond Korea, as it "put K-Pop on the map in a way that no song had really done before". By witnessing this cultural phenomenon alongside her mother, Seoi connected with a defining moment in K-pop history that would ultimately shape her own future.

Her dream of acting in the future

Beyond her current career with H1-KEY, Seoi has expressed interest in expanding her horizons into acting. This aspiration aligns perfectly with her admiration for Son Yejin, one of Korea's most respected actresses.

Remarkably, this dream represents Seoi's ambition to grow beyond her established identity as an idol. Many successful K-pop idols have similarly transitioned into acting roles, utilizing their performance experience and public recognition as a foundation for this career expansion. For Seoi, whose leadership qualities and expressive performance style have already been established with H1-KEY, acting would offer yet another avenue to showcase her artistic versatility.

Fun Facts That Fans Love

Fans of H1-KEY often collect little details about Seoi that reveal her authentic personality beyond performances. These personal tidbits create a deeper connection between the idol and her supporters, offering glimpses into what makes her unique.

Her favorite line from 'Rose Blossom'

When discussing H1-KEY's breakthrough song "Rose Blossom," Seoi expressed particular attachment to the line "Thrive and grow, don't snap". Unlike other members who chose lines that represented strength or ambition, she compared this lyric to "a mother's warm and comfy embrace". For her, these words offer comfort during difficult times, reflecting her nurturing approach as the group's leader. The song itself became a turning point for H1-KEY, with its message of resilience resonating strongly with listeners.

Nicknames and their meanings

Throughout her career, Seoi has accumulated several endearing nicknames that capture different aspects of her character. Initially known as "Iris" and "Cotton Candy", she's now predominantly called "Boss Baby". This latest nickname emerged from the amusing contrast between her position as the eldest member and her remarkably youthful appearance. Her groupmates often use these nicknames affectionately in behind-the-scenes content, highlighting the playful dynamics within H1-KEY.

Her motto and what it says about her

"Seeing the bright side will brighten up my life" serves as Seoi's personal motto, perfectly encapsulating her optimistic worldview. This positive philosophy guides her approach to challenges both within the competitive K-pop industry and daily life. Interestingly, among all H1-KEY members' mottos—ranging from Riina's work ethic focus to Hwiseo's team-oriented perspective—Seoi's stands out as uniquely centered on maintaining a positive mindset. This consistent optimism likely contributed to her perseverance through years of training before finally achieving her debut with H1-KEY.