Ryu Se-il (류세일) is a South Korean actor best known for his work in independent theatre before making a bigger transition into film and television. He has built a reputation through stage productions with the theatre collective Ballplayclub (공놀이클럽) and later expanded his screen career with films and the 2026 Korean BL drama Boy, With Caution.
In Boy, With Caution, Ryu plays Jang Ki-woo, a temporary high-school teacher whose life has been shaped by a damaging rumor from his past. The series pairs him with Ha Jung Hoon, who plays 21-year-old student Lee Hyun-jae. The drama premiered on September 30, 2026, through Heavenly.
Before gaining wider attention through the drama, Ryu was already an award-winning theatre performer. In 2025, he and Ballplayclub received the Young Theatre Award at the 61st Baeksang Arts Awards for Dried Chili Peppers and a Peach-Scented Lipstick.
Ryu Se-il Quick Wiki
| Detail | Information |
|---|---|
| Full Name | Ryu Se-il |
| Korean Name | 류세일 |
| Also Written As | Ryu Seil, Ryu Se Il, Ryoo Se-il |
| Birth Date | August 23, 1991* |
| Age | 35 in 2026* |
| Birthplace | South Korea* |
| Nationality | South Korean |
| Profession | Actor |
| Known For | Boy, With Caution |
| 2026 Role | Jang Ki-woo |
| Theatre Group | Ballplayclub |
| Major Award | 2025 Baeksang Young Theatre Award |
| Agency | UL Entertainment |
| Years Active | 2010s–present |
*Birth information is listed by entertainment databases, but it is not as strongly documented in primary Korean sources as his theatre and acting credits.
Who Is Ryu Se-il?
Ryu Se-il is an actor who spent much of his career developing his craft on the Korean independent theatre scene.
His path was not a typical straight route from television audition to television stardom. According to his biographical profile, he initially had a strong interest in music and played guitar in a school band. After watching One Flew Over the Cuckoo’s Nest, particularly Jack Nicholson’s performance, he became interested in acting.
He later became closely associated with Ballplayclub, a Seoul-based theatre collective known for productions that explore youth, relationships, identity and contemporary social issues.
That theatre background eventually led to recognition at one of South Korea’s major entertainment awards.
Ryu Se-il Age and Birthday
Ryu Se-il is listed as being born on August 23, 1991, which would make him 35 years old in 2026.
However, because his birth information is not consistently presented across major primary entertainment sources, it is better to treat the date as database-reported rather than an independently confirmed fact.
Ryu Se-il Height
A consistently verified official height for Ryu Se-il is not clearly documented in the reliable sources reviewed.
Some online profiles may provide measurements, but those figures should not automatically be treated as official. For a biography page, it is safer to list his height as not publicly confirmed unless his agency or another authoritative source provides it.
Ryu Se-il Education
Ryu Se-il’s professional biography describes him as having studied in a university musical-theatre department, although he later left the program because it did not suit him.
His route into professional acting therefore developed through practical theatre experience and independent productions rather than relying solely on formal university training.
Ryu Se-il Early Life
As a teenager, Ryu was reportedly more interested in music than acting.
He played guitar in a school band and initially imagined pursuing music. His interest changed after seeing Jack Nicholson’s performance in One Flew Over the Cuckoo’s Nest. The film encouraged him to attend an acting academy.
After unsuccessful university entrance attempts, he completed his military service before entering university to study musical theatre.
He eventually found that independent theatre was a better fit for his creative ambitions.
Ryu Se-il and Ballplayclub
A major part of Ryu Se-il’s career is his connection with Ballplayclub (공놀이클럽).
He began collaborating with theatre director and playwright Kang Hoon-gu and became one of the collective’s principal performers. Their work includes productions such as:
- Boy and Girl Evolution Theory
- Phone Seller
- XXL Leotard Anna Sui Hand Mirror
- Rocket Candy
- Burgundy Muki Channel Opening Intro
- Dried Chili Peppers and a Peach-Scented Lipstick
- Madman’s Diary
- Mimi’s Trivial Romance
Ballplayclub has become known for contemporary theatre aimed particularly at young-adult audiences. Seoul’s official cultural information describes the group as a young theatre collective founded in 2018.
Ryu Se-il and Dried Chili Peppers and a Peach-Scented Lipstick
One of the most important productions in Ryu’s career is Dried Chili Peppers and a Peach-Scented Lipstick.
The play explores family relationships, identity and queer themes through a deliberately playful theatrical structure. Its performers switch between characters rather than remaining permanently tied to a single role.
Ryu’s work in the production became a major career milestone when he and Ballplayclub won the Young Theatre Award at the 61st Baeksang Arts Awards in 2025.
Ryu Se-il Baeksang Award
In May 2025, Ryu Se-il and Ballplayclub won the Young Theatre Award in the theatre category at the 61st Baeksang Arts Awards.
The award recognized their work on Dried Chili Peppers and a Peach-Scented Lipstick. Korean reporting noted that Ryu had spent years developing his theatre career and described the award as an important recognition of his stage work.
The award helped bring his name to a wider audience beyond Seoul’s independent theatre community.
Ryu Se-il Theater Career
Theatre remains a central part of Ryu Se-il’s professional identity.
His stage credits have included productions such as Rocket Candy, Orphans, Madman’s Diary, Mimi’s Trivial Romance and other Ballplayclub projects.
In 2026, he appeared in Mimi’s Trivial Romance, alongside Gu Do-gyun, Kim Jeong-a and Park Eun-kyeong. The production was presented through Ballplayclub and directed by Kang Hoon-gu.
He also appeared in Ballplayclub’s 2026 production Madman’s Diary, which ran at Daehangno Theatre Quad in April and May 2026.
Ryu Se-il Movies
Ryu has gradually expanded from theatre into Korean cinema.
His documented film work includes:
The Continuing Land
Ryu appeared as Hwajin in The Continuing Land, directed by Jo Hee-young.
The film premiered at the Seoul Independent Film Festival in 2022 before receiving a Korean theatrical release in 2024.
It Will Only Be Known Differently
Ryu also appeared in the 2025 film It Will Only Be Known Differently, playing Woo-seok.
Woo-seok is described as a warm but sometimes inattentive character whose behavior unintentionally hurts his girlfriend Yoo-jung. The film gave Ryu another opportunity to transfer the detailed character work developed through theatre onto the big screen.
Ryu Se-il in Boy, With Caution
Ryu Se-il’s biggest television role to date is Jang Ki-woo in Boy, With Caution.
The Korean title is 소년, 주의, and the series premiered on September 30, 2026 on Heavenly. It is an eight-episode Korean BL drama directed and written by Lee Son-eum and produced by Nakwon Mansion.
Who Is Jang Ki-woo?
Jang Ki-woo is a 32-year-old temporary high-school teacher.
Four years before the events of the drama, Ki-woo became involved in a damaging rumor involving a student. The incident affected his professional ambitions, and instead of becoming a permanent teacher, he continued moving between temporary teaching positions.
His carefully controlled life changes when he meets Lee Hyun-jae, a 21-year-old student played by Ha Jung Hoon.
The relationship is deliberately complicated by the teacher-student boundary and Ki-woo’s history.
Ryu Se-il and Ha Jung Hoon
In Boy, With Caution, Ryu Se-il stars opposite Ha Jung Hoon.
Ryu plays Jang Ki-woo, while Ha plays Lee Hyun-jae.
The drama’s central storyline follows the two characters as they become increasingly emotionally connected despite the obvious complications surrounding their positions at school.
The pairing also represents an interesting contrast in the actors’ careers: Ryu arrives with years of independent theatre experience and a major theatre award, while Ha is making a much more prominent drama appearance after his earlier acting and modeling work.
Boy, With Caution Cast
The principal cast includes:
| Actor | Character |
|---|---|
| Ryu Se-il | Jang Ki-woo |
| Ha Jung Hoon | Lee Hyun-jae |
| Lee Jung-chan | Kim Jeong-ha |
| Jeong Si-wan | Park Seong-won |
| Park Hong-joon | Choi Young-moon |
| Lee Ha-joon | Lim Hyun-jong |
| Jung Jae-un | Kim Ji-tae |
The series has eight episodes, with the main cast appearing throughout the season.
Ryu Se-il Girlfriend
Ryu Se-il’s current girlfriend or relationship status is not publicly confirmed through reliable sources.
There are no sufficiently reliable public reports establishing a current girlfriend.
His role in Boy, With Caution should also not be used to make assumptions about his private relationships or sexual orientation. His on-screen character is separate from his personal life.
Ryu Se-il Boyfriend
There is no reliable public confirmation of a current boyfriend.
Because Ryu stars in a BL drama, fans may naturally be interested in his personal life, but playing a BL character does not establish an actor’s real-life sexual orientation or relationship status.
For a biography, the safest accurate description is that his relationship status is not publicly confirmed.
Ryu Se-il Family and Parents
Detailed information about Ryu Se-il’s parents, siblings and wider family is not well documented in the reliable public sources reviewed for this biography.
He has largely built his public profile around his theatre and acting work rather than his private family life.
Ryu Se-il Net Worth
Ryu Se-il’s net worth has not been publicly disclosed by a reliable financial source.
He has worked across independent theatre, films and television, but there is no authoritative public figure that establishes his current wealth.
Online celebrity-net-worth estimates should therefore not be presented as confirmed information.
Ryu Se-il Career Highlights
Some of the most important milestones in Ryu Se-il’s career include:
Early career: Develops an interest in acting after initially considering music.
Theatre: Becomes closely associated with Ballplayclub and Seoul’s independent theatre scene.
2022: Appears in The Continuing Land.
2024: Expands his film work and continues major theatre productions.
2025: Wins the Young Theatre Award at the 61st Baeksang Arts Awards with Ballplayclub for Dried Chili Peppers and a Peach-Scented Lipstick.
2025: Appears in It Will Only Be Known Differently.
2026: Continues stage work with Ballplayclub, including Mimi’s Trivial Romance and Madman’s Diary.
September 30, 2026: Makes his leading BL drama debut as Jang Ki-woo in Boy, With Caution.
Ryu Se-il Filmography
Movies
- The Continuing Land — Hwajin
- It Will Only Be Known Differently — Woo-seok
Drama
- Boy, With Caution — Jang Ki-woo
Selected Theatre
- Rocket Candy
- Dried Chili Peppers and a Peach-Scented Lipstick
- Orphans
- Madman’s Diary
- Mimi’s Trivial Romance
His theatre résumé is considerably larger than his currently documented television résumé, which reflects how long he has worked on stage before moving into more prominent screen roles.
Ryu Se-il Frequently Asked Questions
How old is Ryu Se-il?
Some professional entertainment databases list Ryu Se-il as born August 23, 1991, making him 35 in 2026. Because this information is not consistently documented in primary sources, it should be treated as database-reported.
What is Ryu Se-il famous for?
He is particularly known for his award-winning independent theatre work and, in 2026, for playing Jang Ki-woo in Boy, With Caution.
What role does Ryu Se-il play in Boy, With Caution?
He plays Jang Ki-woo, a temporary high-school teacher whose career was affected by a past rumor involving a student.
Has Ryu Se-il won an award?
Yes. He and Ballplayclub won the Young Theatre Award at the 61st Baeksang Arts Awards in 2025 for Dried Chili Peppers and a Peach-Scented Lipstick.
Is Ryu Se-il a theatre actor?
Yes. Theatre has been a major part of his career, particularly through his work with Ballplayclub. Seoul cultural records continue to list him in the collective’s productions.
Does Ryu Se-il have a girlfriend?
His current relationship status has not been publicly confirmed through a reliable source.
Is Ryu Se-il married?
There is no reliable public information confirming that Ryu Se-il is married.
Is Ryu Se-il gay?
His personal sexual orientation has not been publicly confirmed in the reliable sources reviewed. His appearance in a BL drama does not establish his real-life sexuality.
What movies has Ryu Se-il appeared in?
His documented film credits include The Continuing Land and It Will Only Be Known Differently.
Final Thoughts
Ryu Se-il’s career is rooted in theatre rather than celebrity-driven television.
Years of work with Ballplayclub helped him establish himself in Seoul’s independent theatre community, and his performance in Dried Chili Peppers and a Peach-Scented Lipstick eventually brought him the Young Theatre Award at the 2025 Baeksang Arts Awards.
His move into more visible screen work has been gradual. After appearing in independent films, Ryu reached a much wider audience in 2026 with Boy, With Caution, where he takes on his first major BL drama lead as Jang Ki-woo.
For viewers discovering him through the drama, his theatre background provides useful context: Ryu Se-il was already an established stage performer before becoming a more recognizable screen actor.
