Kim Siyoon

Kim Si-yoon is a South Korean singer, rapper, and actress best known as a member of the girl group Billlie. She serves as one of the group's primary vocalists and rappers while also carving out a distinct path as an emerging film star.

As of 2026, she stands at 167 cm tall and has built a reputation for her unique vocal tone and authentic personality on variety shows. Her career trajectory shifted significantly in 2026 when she secured a lead role in the Hollywood thriller Perfect Girl, marking her first major acting venture outside of South Korea. [edit]

Kim Si-yoon grew up in Gwangmyeong, Gyeonggi-do, where she attended Gwanghee Middle School before focusing entirely on her performing arts education. Before stepping into the spotlight, she navigated a rigorous selection process that began in early 2020. MYSTIC STORY announced seven rookie candidates at the time, and Siyoon was among those selected to undergo intensive training in singing, rapping, dancing, and acting.

The agency spent over a year preparing the trainees for their eventual debut. During this period, Siyoon honed her skills alongside future bandmates, refining her stage presence and vocal range. The training phase involved grueling schedules designed to prepare them for the competitive K-pop landscape. Her breakthrough moment arrived in November 2021 when Billlie officially debuted with the mini-album The Billage of Perception: Chapter One. The group introduced a unique 'phantom' concept that immediately captured attention, setting the stage for Siyoon's rise as a versatile performer. [edit]

Billlie made a strong entrance in November 2021 with The Billage of Perception: Chapter One, quickly gaining traction for their dark fantasy aesthetic and powerful performances. Siyoon contributed significantly to the group's sound with her distinctive voice and lyrical input. The success continued with subsequent releases like The Billage of Perception: Chapter Two in 2022, which solidified their place in the fourth generation of K-pop.

In 2023, she expanded her artistic range by forming the sub-unit Moon Sua X Siyoon, releasing collaborative tracks that highlighted her chemistry with fellow member Moon Sua. Her versatility caught the eye of international producers, leading to a pivotal career shift in mid-2026. She was cast as the lead actress in Perfect Girl, a high-profile K-pop thriller produced by Atlantic Records and The Black Label. This role marked her transition from idol to global screen star, with production confirmed by November 2026. [edit]

Siyoon projects an image that blends cool, edgy rap energy with the warmth of a relatable variety show personality. She is frequently described as having a 'unique color' in her vocals and a strong sense of self-awareness regarding her mental health and personal boundaries. Her fashion choices often reflect the group's dark fantasy aesthetic while maintaining a modern streetwear edge. Media outlets highlight her authenticity, particularly after her candid discussions about OCD traits and her supportive nature toward colleagues facing online harassment. [edit]

As of the August 2026 rankings, Siyoon holds a prominent position among rising global stars, reflecting her dual success in music and film. She is featured at No. 12 in the August 2026 iFAMOUS Rankings, a testament to her expanding influence beyond the K-pop sphere. The official fandom name for Billlie is Meeli, and these fans refer to themselves collectively as such. They are highly organized, participating in chart pushes, birthday campaigns, and charity drives in Siyoon's name. Notable fan projects include creative video edits and fan art that celebrate her acting debut in Perfect Girl. Siyoon interacts with Meeli through live streams and fan meetings, often sharing personal thoughts and gratitude for their unwavering support. [edit]

On the variety show My Little Old Boy in August 2025, Siyoon humorously revealed she has mild OCD traits, specifically sharing a funny anecdote about her struggle with her girlfriend's flatulence that went viral among fans. In March 2025, her comments defending the late actress Kim Sae Ron against online hate resurfaced, showcasing her empathy and support for peers in the industry. Fans often recall her candid admission about her ideal type and future plans for children on a TV show in August 2025, noting her mature perspective despite her young age. Her debut performance with Billlie remains iconic for its theatricality and the group's unique phantom concept. The casting announcement for Perfect Girl is considered a defining moment, marking the first time a Billlie member took on a lead role in a major Hollywood production backed by US record labels. [edit]

Kim Si-yoon was born to parents who supported her dream of becoming a performer from a young age. While details about her siblings remain private, she has mentioned her family's encouragement during her trainee years. She currently resides in the Gwangmyeong area near her hometown. Her close bond with her group members often feels like a second family, especially given the intense training schedule they shared. She keeps her personal life strictly separate from her public persona, rarely discussing specific family members in interviews. [edit]

Moon Sua, MYSTIC STORY, Arin, Suhyeon, Hyunjin, Huiyeon, Tsuki, Beomseok. [edit]

As of 2026, there are no publicly confirmed romantic relationships, engagements, or marriages involving Kim Si-yoon. She is widely reported to be single. Unlike many adult idols who may have publicized relationships, Siyoon, having debuted at age 16 and remaining active in her early 20s, has maintained a private personal life. There are no credible reports of past flings, breakups, or dating history in mainstream media or fan communities. She has not disclosed any partners, nor are there rumors of secret relationships that have been substantiated by multiple outlets. Her public appearances focus entirely on her music, variety show segments, and acting projects. As of late 2026, she remains unattached and focused on her expanding career in both K-pop and international cinema. [edit]

iFANN Editorial Team research estimates Kim Si-yoon's net worth at approximately $960,000 as of 2026. This figure reflects her earnings from album sales, streaming revenue, and endorsement deals with fashion and beauty brands common for idols. Her monthly salary from MYSTIC STORY and royalties from Billlie's discography form the base of her income. The upcoming contract for Perfect Girl likely added a significant signing bonus or salary to her assets. Unlike senior idols, she is still building her independent wealth, but her recent Hollywood breakthrough suggests rapid growth. Real estate holdings are not publicly documented, and her financial portfolio remains primarily tied to entertainment contracts. [edit]

Billlie has won several Rookie of the Year awards upon debut and subsequent year-end awards for rising artist recognition. While specific individual awards for Kim Si-yoon are limited, her primary accolades stem from the group's success, including consistent performance on music charts and 'Rookie of the Year' titles across various ceremonies in 2021-2022. [edit]