Five demons. One boy band. And a cast of real-life talent most fans never expected. The Saja Boys from Netflix’s K-Pop Demon Hunters took over global charts before viewers even stopped to ask who was behind those voices.
Each character has two people bringing them to life: a speaking actor for dialogue and a professional singer for the music. That split-casting choice is a big reason the songs hit differently.
We cover the full lineup of Saja Boys voice actors, what each performer is known for, and a few details about how they landed the roles.
If you have been searching for the complete cast of speakers and singers, here it is.
The Cast at a Glance
Below is a quick cast breakdown, showing each Saja Boys member with their speaking performer and singing voice.
| Character | Speaking Voice | Singing Voice |
|---|---|---|
| Jinu Saja | Ahn Hyo-seop | Andrew Choi |
| Abby Saja (also credited as Abs) | SungWon Cho (ProZD) | Neckwav |
| Mystery Saja | Alan Lee | Kevin Woo |
| Romance Saja | Joel Kim Booster | Samuil Lee |
| Baby Saja | Danny Chung | Danny Chung |
One Character, Two Voices: How the Saja Boys Were Cast
Director Maggie Kang and co-director Chris Appelhans built the Saja Boys with a deliberate split in casting.
Speaking actors handle all dialogue scenes, while separately credited singing performers deliver the vocals on the soundtrack.
The result is a group where the acting voice and the singing voice belong to entirely different people for most members. Only one exception exists: Danny Chung, who serves as both the speaking and singing voice for Baby Saja.
Co-director Appelhans told Netflix that the team wanted the Saja Boys’ songs to feel “super catchy, but slightly hollow, like there’s no real soul underneath,” unlike the girl group Huntrix.
That intentional sonic contrast shaped who they cast on the singing side.
Meet the Saja Boys: Voice Cast and Vocal Performers
The Saja Boys feature a mix of voice actors and singers, with each member brought to life through unique dual performances that combine dialogue delivery and musical talent.
Jinu Voice Actor and Singer
Jinu’s character is brought to life through a dual performance, with Ahn Hyo-seop handling the speaking role and Andrew Choi delivering the singing voice.
As the central figure of the Saja Boys, Jinu carries emotional weight and narrative importance throughout the film.
Ahn Hyo-seop provides a composed yet intense vocal presence that anchors the character, while Andrew Choi contributes a smooth and powerful musical tone.
This combination ensures that Jinu stands out in both dialogue and songs, making him one of the most recognizable and most frequently searched members.
Abby Voice Actor and Singer
Abby’s character features a split performance, with SungWon Cho, widely known as ProZD, voicing the dialogue and Neckwav providing the singing voice.
SungWon Cho brings a distinctive, expressive tone that complements the animated style, giving Abby a memorable personality.
Meanwhile, Neckwav enhances the musical side with a sharper, more defined vocal presence across songs.
Abby often appears in fan searches due to slight variations in name listings, but the pairing remains consistent: SungWon Cho for speaking and Neckwav for singing.
Mystery Voice Actor and Singer
Mystery is portrayed through the combined talents of Alan Lee as the speaking voice and Kevin Woo as the singing voice.
This pairing draws particular attention because Kevin Woo is recognized by many fans as a former member of the K-pop group U-KISS.
Alan Lee establishes Mystery’s personality through dialogue, while Kevin Woo contributes polished, professional vocals that elevate the group’s musical performances.
This blend of acting and real-world idol experience makes Mystery especially popular among fans and strengthens the connection between the fictional group and authentic K-pop influences.
Romance Voice Actor and Singer
Romance is voiced by Joel Kim Booster, with SamUIL Lee providing the singing voice, creating a balanced and expressive portrayal of the character.
Joel Kim Booster delivers a lively, dramatic tone that highlights Romance’s personality in spoken scenes.
In contrast, SamUIL Lee brings a refined and polished vocal quality to the musical performances, ensuring the character fits seamlessly into the group’s songs.
This dual-casting approach allows Romance to stand out as one of the more expressive members, blending strong character delivery with a smooth, engaging musical presence.
Baby Voice Actor and Singer
Baby is uniquely performed by Danny Chung, who handles both the speaking and singing roles, setting him apart from the other Saja Boys members.
This unified performance creates a consistent voice across both dialogue and musical scenes, giving the character a cohesive identity.
Danny Chung’s dual role simplifies the casting structure and makes Baby easy for fans to identify when reviewing the full cast list.
Unlike the others, there is no separate singer to track, making Danny Chung the single name associated with Baby’s complete performance.
What the Split-Cast Approach Adds to the Characters
Casting separate speaking and singing performers for animation is not new, but the Saja Boys’ vocal team was built with an industry depth that set it apart. Andrew Choi spent years composing at SM Entertainment.
Kevin Woo performed as an active idol with U-KISS. Danny Chung works as an A&R executive at THEBLACKLABEL.
SamUIL Lee and Neckwav are both working artists in Seoul. That collective experience gave the songs a credibility that is hard to fake.
It also freed the speaking actors to focus entirely on character work, without dividing their attention between dialogue and vocal performance.
The Saja Boys’ Songs and Chart Impact
The soundtrack for K-Pop Demon Hunters debuted at number 8 on the Billboard 200, making it the highest-charting soundtrack of 2025 at the time.
Four songs from the film appeared in the top ten of the US Billboard Hot 100 simultaneously, a first for any film soundtrack in the chart’s history.
The soundtrack was produced by a team that included Teddy Park of The Black Label, known for his work with BLACKPINK and 2NE1, as well as producers Lindgren and 24.
Songs were co-written by Danny Chung, Ejae, Jenna Andrews, Stephen Kirk, and others.
Wrapping Up
The Saja Boys work as well as they do because the people behind them knew exactly what they were doing.
Ahn Hyo-seop lends K-drama credibility to Jinu’s conflicted arc, while Andrew Choi carries the emotional weight of every song with a voice built on years of behind-the-scenes work in the industry.
SungWon Cho, Alan Lee, and Joel Kim Booster give the other three members sharp, distinct personalities. Kevin Woo, Neckwav, SamUIL Lee, and Danny Chung make sure the music holds up on its own terms.
If you have not watched K-Pop Demon Hunters yet, now you know exactly who to listen to. Drop a comment below and let us know which Saja Boy is your favorite!
Frequently Asked Questions
Is Kevin Woo a Real K-Pop Singer or Just a Voice Actor?
Kevin Woo is a real K-pop artist. He was a member of the group U-KISS before joining the film as the singing voice of Mystery Saja.
What Other Projects is Sung Won Cho Known for Outside This Film?
SungWon Cho, known online as ProZD, has voiced characters in Solo Leveling, Sakamoto Days, One Piece, Aggretsuko, and Craig of the Creek. He built his reputation through YouTube before moving into professional voice work.
Is Kevin Woo One of The Animated Members?
Kevin Woo is not shown as himself. He provides Mystery’s singing voice, giving that character a real K-pop vocal connection through his background with U-KISS.
