Discover everything about Siyoon from Billlie – biography, career, pre-debut journey, and her impact in K-pop.
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| Photo of Kim Siyoon (김시윤) of Billlie. |
Who is Kim Siyoon?
Siyoon (Korean: 시윤), born Kim Si-yoon on February 16, 2005, is a South Korean rapper, singer, and dancer under Mystic Story. She is a core member of the K-pop girl group Billlie, known for their concept-driven music and strong storytelling. Siyoon is celebrated for her powerful rap delivery, stage presence, and lyrical contributions to the group’s tracks.
Kim Siyoon (Billlie) – Biodata
Biodata table of Siyoon from Billlie – Get detailed personal and professional information about the K-pop idol.
| Full Real Name | Kim Si-yoon |
|---|---|
| Name in Hangul | 김시윤 |
| Stage Name | Siyoon (시윤) |
| Date of Birth | February 16, 2005 |
| Place of Birth | Gwangmyeong, Gyeonggi-do, South Korea |
| Occupation | Singer, Rapper, Dancer, Model |
| Gender | Female |
| Blood Type | B |
| Height | 173cm (tallest in Billlie) |
| MBTI | INFP |
| Nationality | South Korean |
| Education | Trained at Def Academy & Millennium Dance Academy |
| Hobbies | Writing lyrics, fashion modeling, photography |
- Other Work: Regular model for Japan’s Popteen magazine
Kim Siyoon (Billlie) – Biography
Complete biography of Siyoon from Billlie, covering her early life, training, debut, career achievements, and personal facts.
Early Life and Background
Kim Si-yoon, known professionally as Siyoon, was born on February 16, 2005, in Gwangmyeong, Gyeonggi-do, South Korea. From a very young age, Siyoon displayed a passion for the performing arts. Her early television appearance came in 2009 when she performed on SBS’s Star King as part of the “Baby Wonder Girls,” drawing national attention for her charisma and talent.
Siyoon later trained at prestigious institutions such as Def Academy and Millennium Dance Academy, where she honed her skills in dance, rap, and performance. Her dedication led her to pass an audition for Mystic Story in 2019.
Training and Pre-Debut Activities
Siyoon was introduced as part of Mystic Rookies on February 18, 2020. Even before debuting, she had appeared in BOYFRIEND’s “Love Style” teaser video and featured in a 2015 Reuters photo essay that explored the lives of aspiring K-pop trainees in South Korea. Her background gave her a unique edge in the industry, making her debut one of the most anticipated among rookie idols.
Debut with Billlie
On November 10, 2021, Siyoon debuted as a member of the girl group Billlie under Mystic Story with the mini-album The Billage of Perception: Chapter One. The title track, “Ring X Ring,” immediately showcased her confident rap style and on-stage charisma.
Billlie’s musical identity is built on a rich, lore-heavy narrative, and Siyoon’s versatility allowed her to play a significant role in the group’s evolving concept. She has contributed lyrically and vocally to several tracks in Billlie’s expanding discography.
Moon Sua X Siyoon Sub-Unit
In April 2025, Siyoon partnered with fellow Billlie member Moon Sua to form the sub-unit Moon Sua X Siyoon. Their debut digital single SNAP was met with acclaim for its bold visuals and genre-blending sound, signaling a more mature artistic direction.
Modeling and Public Image
In addition to her musical career, Siyoon is known for her modeling. She has been a regular model for Popteen, a popular Japanese teen fashion magazine. Her tall stature (173 cm), expressive features, and trendy style have helped solidify her image as both an idol and fashion icon.
Personal Life and Interests
Siyoon is known for her warm, introspective personality, reflected in her MBTI type: INFP. She enjoys writing lyrics, taking aesthetic photos, and studying fashion. Fans often praise her for being articulate, down-to-earth, and emotionally expressive both on stage and off.
Legacy and Influence
Despite her young age, Siyoon has already made a notable impact in the K-pop world. With a unique voice, strong artistic instincts, and a clear vision for her career, she continues to evolve as one of the most promising artists of her generation. As Billlie’s discography grows and new projects emerge, Siyoon remains at the forefront, captivating fans across the globe.
Interesting & Fun Facts About Kim Siyoon (Billlie)
Quick facts about Siyoon from Billlie – personal details, career milestones, and fun trivia.
- Full Real Name: Kim Si-yoon
- Name in Hangul: 김시윤
- Stage Name: Siyoon (시윤)
- Date of Birth: February 16, 2005
- Place of Birth: Gwangmyeong, Gyeonggi-do, South Korea
- Occupation: Singer, Rapper, Dancer, Model
- Group: Member of K-pop girl group Billlie under Mystic Story
- Sub-unit: Moon Sua X Siyoon (debuted April 2025 with single “SNAP”)
- Debut Date: November 10, 2021 (with Billlie’s mini-album The Billage of Perception: Chapter One)
- Height: 173 cm (tallest member of Billlie)
- Blood Type: B
- MBTI: INFP
- Nationality: South Korean
- Education/Training: Trained at Def Academy & Millennium Dance Academy; joined Mystic Story in April 2019; introduced as Mystic Rookies February 2020
- Pre-debut Appearance: Appeared on SBS’s Star King (2009) as part of “Baby Wonder Girls”
- Modeling: Regular model for Japan’s teen fashion magazine Popteen
- Hobbies: Writing lyrics, Fashion modeling, Photography
- Fandom Name: Unicity
Why Siyoon Stands Out in K-Pop
Siyoon’s charisma, tall stature, and lyrical prowess set her apart in the competitive K-pop scene. She represents a new generation of idols who combine visual appeal with deep artistic input. Whether rapping on stage or sharing behind-the-scenes moments on social media, Siyoon connects deeply with fans worldwide.
Kim Siyoon (Billlie) – Social Media Accounts
Fans can check her latest updates on Siyoon’s Instagram @see_uniuni .
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