Who Are the Saja Boys? Jinu, Mystery, Romance, Baby & Abby from K-Pop Demon Hunters Fully Explained
Who Are the Saja Boys? Jinu, Mystery, Romance, Baby & Abby from K-Pop Demon Hunters Fully Explained
They debuted without warning. They had the choreography, the visuals, the hooks, and the kind of effortless charisma that makes the entire K-pop industry stop and stare. Their first performance of "Soda Pop" sent the internet into a spiral. Fan cams. Edit compilations. Trend cycles. Millions of people declaring their bias within forty-eight hours of meeting them for the first time.
The only problem? The Saja Boys are demons. Actual demons. In disguise. Draining the souls of every fan who falls in love with them to feed to their master, the Demon King Gwi-Ma, while simultaneously dismantling the magical barrier protecting the human world from the demon realm.
And the fandom loves them anyway.
The Saja Boys are the rival boy band at the center of K-Pop Demon Hunters, and they are one of the most compelling villain groups in modern animation. On the surface they are five staggeringly attractive K-pop idols. Underneath — they are demons with centuries of history, complicated motivations, and at least one member with a story that will shatter you if you let it.
This is everything you need to know about the Saja Boys: who they are, where they came from, what they want, and why the fandom refuses to stop talking about them.
The Saja Boys: Origins and Formation
To understand the Saja Boys you have to understand where their name comes from — because like almost everything in the K-Pop Demon Hunters universe, nothing about them is accidental.
Saja derives from the Korean word for lion, which gives the group their distinctive lion-themed iconography and visual identity. But it also references something deeper: in Korean spiritual tradition, the Jeoseung Saja are the supernatural figures responsible for guiding the souls of the deceased from the human world to the afterlife. They are, in a sense, death's collectors — beings who stand at the threshold between worlds and escort souls across it.
In the film's mythology, Gwi-Ma has taken this concept and corrupted it entirely. His Saja Boys don't guide souls peacefully to their natural destination. They steal them — extracting the spiritual energy of living fans against the natural order and funneling it to the Demon King. Five creatures who were designed by cosmic tradition to bring peaceful transition to the dead have been conscripted to violently harvest the living. The name that should represent one of the most solemn and sacred functions in Korean spiritual belief has been turned into a pop group brand.
The Saja Boys exist because Jinu proposed them. After generations of Gwi-Ma's demons failing to destroy the Honmoon through direct combat, Jinu — the most human-minded demon in Gwi-Ma's service — looked at the problem differently. HUNTR/X draw their power from fans. The Honmoon is powered by the collective emotional energy of people who love them. So the solution is not to fight HUNTR/X. The solution is to take the fans.
Gwi-Ma, initially skeptical, approved the plan. The Saja Boys were formed. And within weeks of their debut, their "Soda Pop" performance had the human world completely captivated — exactly as planned.
Jinu: The Tragic Leader
Of all five Saja Boys, only one receives a full character arc. Only one is given the space to be more than a charming, dangerous demon. Only one, as director Maggie Kang has noted, still has a tinge of his soul left.
That is Jinu.
Jinu is the undisputed center of the Saja Boys — their leader, main vocalist, creative strategist, and the character whose story gives the entire group its emotional weight. He is voiced by Korean actor Ahn Hyo-seop in his first animated and first villainous role, with Andrew Choi providing his singing voice. His character design draws inspiration from Korean actor and idol Cha Eun-woo alongside actors Nam Joo-hyuk — a visual reference point that explains immediately why half the fandom considers him simultaneously the most beautiful and the most devastating character in the film.
He is also over four hundred years old.
Jinu was born in the 1600s during Korea's Joseon era — specifically, his age was set to four hundred years to place his origin during the reign of King Gwanghae in the early seventeenth century. He grew up in deep poverty alongside his mother and younger sister, and the weight of watching his family suffer was unbearable. When Gwi-Ma approached him with an offer — a powerful, heavenly singing voice and the wealth and recognition that would lift his family from poverty — Jinu said yes.
He should not have said yes.
The deal brought everything it promised. Fame. Recognition. The ability to provide for his family in ways he never could before. And then — because this is Gwi-Ma, who gives nothing without taking everything — Jinu found himself condemned to the demon world, separated from the family he had sacrificed to help, watching from across an impassable threshold as his mother and sister's lives fell apart without him. The wealth meant nothing without him there. The recognition meant nothing to people who had lost their son and brother.
Four hundred years later, Jinu is still carrying that guilt. It has kept him enslaved to Gwi-Ma more completely than any physical chain could. He cannot leave because every time he thinks about leaving, the shame of what he did to his family collapses him. Gwi-Ma does not need to hold him captive. He holds himself captive.
His plan with the Saja Boys was driven, in part, by a private deal within the deal: if he helped Gwi-Ma destroy the Honmoon, Gwi-Ma promised to erase Jinu's painful human memories. Not redemption. Not freedom in any meaningful sense. Just the erasure of the grief that had been his prison for four centuries. He didn't want to stop suffering. He had given up on that. He just wanted to stop remembering why he was suffering.
This is what makes Jinu such an extraordinary character. He is not simply a villain seeking power. He is a profoundly damaged person — or what was once a person — who has been kept in bondage by his own unresolved guilt for so long that he has mistaken the absence of memory for the possibility of peace.
His relationship with Rumi is the emotional axis around which his arc rotates. When Jinu discovers during their first fight that Rumi has demon markings — the same spreading patterns that mark those touched by Gwi-Ma's influence — his reaction is not to exploit the vulnerability immediately. He hides it from the other Saja Boys. He keeps her secret. And then he meets with her privately to tell her what the markings mean, what shame does to the demons it marks, and what happened to him four hundred years ago.
It is the most honest thing Jinu has done in centuries. He admits, in that conversation, that shame enslaves demons through voices — the constant internal chorus of what you did wrong, what you are, what you deserve. He tells Rumi his truth: that Gwi-Ma granted him fame that helped his family emerge from poverty, then condemned him to the demon world, and that the guilt over his family's downfall has never left him. He tells her this not entirely as manipulation — though it functions as that too — but because something in him recognized that Rumi was the first person in four hundred years who could actually understand what he was carrying.
Their subsequent relationship is one of the most complicated in the film. They heal each other in ways neither anticipated. Rumi tells Jinu that her shame about her demon heritage had weakened her voice, but talking with him restored it. Jinu tells her that he no longer hears the voices, thanks to her. These are not performances. They are genuine. And that genuine connection is exactly what makes Jinu's eventual betrayal — when Gwi-Ma forces him back into submission — so painful to watch.
He did not want to betray her. He had tried to choose her. Gwi-Ma simply reminded him, with devastating precision, of the truth Jinu had been trying to outrun for four hundred years: that he abandoned his family for a life of wealth and comfort, and that no amount of connection with Rumi would ever erase that fact.
Jinu breaks back under the weight of the same guilt that had always broken him. He sets the trap. He destroys the Idol Awards performance. He watches Rumi flee the stage as her demon nature is exposed to the world.
And then, in the film's final act, something shifts.
As Gwi-Ma grows powerful enough to physically enter the human world and targets Rumi directly for the killing blow — Jinu steps in front of it. He takes the attack meant for Rumi. He uses the last of his strength to transfer his restored soul to her, empowering HUNTR/X for the final battle and contributing the energy that creates the new Honmoon.
He does not survive it. Whether his sacrifice erased him entirely or sent his soul somewhere it could finally rest is left deliberately ambiguous — a question that the confirmed sequel will presumably address. But the choice itself is unambiguous: Jinu, who had spent four hundred years enslaved by the shame of choosing himself over his family, made his final choice for someone else.
Ahn Hyo-seop, who voices him, explained his character simply and precisely: Jinu made a very dangerous but life-changing decision to protect his family, and that choice led to suffering and being trapped in darkness with his soul under Gwi-Ma's control. Despite all of that, Jinu still holds onto warmth and has a deep sense of love and curiosity about humanity.
One detail the fandom discovered, and which the official KPDH Fandom wiki confirms: if you listen very carefully to the background harmonies of "What It Sounds Like" — the song Rumi sings that breaks the trance, saves Mira and Zoey, and defeats Gwi-Ma — you can faintly hear Jinu's voice woven into the texture. He was there, even at the end. He was always there.
His name, the directors have noted, is a deliberate nod to the real-world Korean duo JinuSean — a common Korean name, like John in English, chosen to emphasize his ordinariness. He was not born special. He was born poor, and scared, and desperate to help his family. That is what makes his story so devastating. He was simply human, once. The most human of the Saja Boys by an enormous distance. And the most human thing about him was the mistake he could never stop punishing himself for.
Mystery: The Silent One
The second member of the Saja Boys is the group's most deliberately opaque character, which suits him perfectly. Mystery — his stage name, his role, and arguably his entire personality — is the one you never quite get a read on.
Mystery is the group's main dancer. His combat style mirrors his performance style: fluid, precise, and deeply unsettling in its grace. He moves through a fight the same way he moves through choreography — as if every moment is already known to him, every outcome already arranged. He is the best at sensing supernatural disturbance before it manifests, functioning as the Saja Boys' early warning system for spiritual threats.
Visually, Mystery was designed with a specific and fascinating reference point. While Jinu's design was inspired by Korean actors Cha Eun-woo and Nam Joo-hyuk, Mystery's visual aesthetic was inspired by anime men — a deliberate tonal distinction that sets him apart from the rest of the group as something that exists slightly outside of ordinary human visual reference.
He does not speak much. What he does say tends to land with disproportionate weight precisely because of how rarely he chooses to say anything. The fandom has developed enormous affection for Mystery for exactly this reason — he is a canvas onto which imagination can project freely, which is perhaps the most fitting thing that could be said about a character whose entire identity is built around withholding information.
The director's confirmed intention was for Mystery and the other non-Jinu Saja Boys to function as characters who are more far gone as demons — further from their humanity, less recoverable — in order to make Jinu's retained warmth stand out more clearly. In that sense, Mystery's inscrutability is not a limitation of his character development but a deliberate choice about what he represents: a demon who has been a demon for long enough that the person he once was is no longer legible.
A sequel would presumably give him the space to become legible. Fans are waiting.
Romance: The Visual
In most K-pop boy groups, the visual member is the one whose role is simply to exist at a level of attractiveness that destabilizes everyone in the room. Romance fulfills this function so completely that his stage name requires no explanation whatsoever.
Romance is the Saja Boys' designated heartthrob — the member whose function within the group's fan-manipulation strategy is to be so extraordinarily good-looking that the people he targets are completely disarmed before a single soul-draining note has been played. He is effective at this in a way that even the other Saja Boys appear to find slightly excessive.
Beyond his visual role, Romance is the member most associated with performance charisma at close range — while Jinu commands the stage from its center with leadership energy, Romance works the edges, the fan interactions, the individual moments of eye contact that make a single person in a crowd feel specifically chosen. These are, of course, weapons. But they are weapons deployed with considerable skill.
Romance's design draws from the broader vision board of K-pop boy group aesthetics that the creative team assembled during production. The directors consulted references including TXT, BTS, Stray Kids, ATEEZ, BIGBANG, and MONSTA X when developing the Saja Boys' overall visual language, and Romance is perhaps the member who most completely synthesizes those references into a single, overwhelming impression.
His backstory, like Mystery's, is not explored in the film. He is, as director Kang confirmed, more fully a demon — more far gone from whatever human origin he may have had. The warmth that flickers visibly in Jinu is not visible in Romance. What is visible instead is the polished, devastating performance of warmth. Which, in its own way, is even more disturbing.
Baby: The Maknae
Every K-pop group has a maknae — the youngest member, often the most playful, the one who gets away with things that nobody else could. In the Saja Boys, that role belongs to Baby.
Baby is the Saja Boys' maknae in terms of group dynamic, though not necessarily in terms of absolute age — the exact timeline of when each non-Jinu member became a demon is not established in the film. What is established is his energy: quick, unpredictable, and operating on a frequency that is slightly faster than everyone around him.
His combat specialty is speed. Among the Saja Boys, Baby is the fastest fighter — difficult to track, difficult to pin, difficult to counter because he is rarely where he appears to be for long enough for a counter to land. Zoey, who fights with similar quickness and relies on precision thrown weapons, is his natural counterpart in the HUNTR/X fights. Their battles have a kinetic energy that is distinct from the heavier, more forceful exchanges between Mira and Abby or the more psychologically complex encounters between Rumi and Jinu.
Baby's visual energy reflects his role — there is a brightness to him, a surface lightness, that makes him stand out from the more moody or intense aesthetics of the other members. Fans have noted that he gives the group's lineup a necessary lightness that keeps the Saja Boys from being one-dimensionally threatening. Even demon boy bands need someone who makes you want to smile before they drain your soul.
Abby: The All-Rounder
The fifth and final Saja Boy is Abby — credited officially in the film's credits as Abs, though referred to as Abby throughout the film itself and by director Maggie Kang in interviews. Both names are used in fandom contexts. His name is, as confirmed by the production team, a reference to his physical design, which leans into the K-pop tradition of the all-rounder demonstrating physical excellence in multiple forms.
Abby is the group's all-rounder: the member without a single defining specialty because he does everything competently. He can sing. He can dance. He can fight. He handles whatever the situation requires. In K-pop group dynamics, the all-rounder is often the most quietly essential member — the one who stabilizes the group when specialists are occupied with their specialties, the one who plugs whatever gap has opened up.
In combat, Abby is the most physically imposing of the Saja Boys and typically takes point in group confrontations. His fights with Mira — who is similarly direct and physically powerful — are among the film's most dynamic exchanges. Both of them fight as if the solution to every problem is to hit it hard enough and trust that the problem will eventually agree.
Abby is the only non-Jinu Saja Boy who receives a physically distinctive design element in the film. The production team confirmed, in a detail that became a running joke in the fandom, that all five Saja Boys have fully rendered physical details under their clothing — but the show-off privilege went to Abby alone.
The Saja Boys as a Mirror of K-Pop's Dark Side
Understanding the Saja Boys as characters requires understanding what they represent within the film's larger commentary on K-pop culture itself.
Every element of the Saja Boys' function in the story is a pointed observation about how entertainment can be weaponized. They debut with manufactured perfection — polished choreography, irresistible songs, carefully calibrated personas for each member. They deploy an engagement playbook that is indistinguishable from legitimate idol group strategy. They make fans feel seen, specifically chosen, personally connected to performers who do not actually know they exist. And then they drain exactly the energy those feelings generate.
The critical detail is that the Saja Boys do not create the connection that allows them to drain fans. The fans create it themselves, because the performance is good enough to invite it. This is the film's uncomfortable observation about parasocial relationships in K-pop fandom: the vulnerability is real, the feelings are real, and they exist regardless of whether the idols who inspired them are genuinely reciprocating or not.
HUNTR/X are the answer to this critique rather than its subject. The Honmoon works because the connection between HUNTR/X and their fans is real — the girls genuinely pour themselves into their music, genuinely care about the people who love them, and create a real exchange of energy rather than a one-directional extraction. But the film is honest enough to acknowledge that from the outside, before you know the truth, the Saja Boys look identical to HUNTR/X. Charismatic idols. Catchy songs. An audience that loves them.
The difference is what happens to the audience afterward.
The Saja Boys' Fandom: Why Fans Love the Villains
The Saja Boys achieved something remarkable in the K-Pop Demon Hunters fandom: they became genuinely beloved despite being the film's primary antagonists. Their merchandise appears throughout the fandom with no apparent irony. Their music charted independently of whether fans knew or cared about their in-universe role as soul-drainers. The Funko Pop! chase variant of Demon Jinu in his "Soda Pop" bubblegum look became one of the most hunted collectibles in the entire lineup.
This is not unusual for well-written villain groups in media — the history of beloved fictional antagonists is long and storied. But the Saja Boys earn their fandom placement specifically because of Jinu's arc, which functions as a proof of concept that the rest of the group's stories are worth caring about too. If Jinu — who did actively terrible things and hurt Rumi in specific, personal ways — can be loved because his tragedy is real and his final choice was genuinely redemptive, then Mystery, Romance, Baby, and Abby occupy an interesting position: characters whose fuller stories have not yet been told, whose humanity (or former humanity) has not yet been excavated, and whose potential for complexity the sequel is now theoretically positioned to explore.
Director Maggie Kang has confirmed that the Saja Boys were deliberately left less developed than Jinu because the film did not have the runtime to give them proper arcs that would tie into the shame and acceptance theme. She also confirmed that the sequel is naturally set up to explore more of the demons' psyches. The fandom, which has been building elaborate headcanons for Mystery, Romance, Baby, and Abby for months, is very much ready for that exploration.
After the film's climax, a single visual detail tells the Saja Boys' ending as efficiently as any dialogue could: their merchandise appears discarded in a trash bin outside Namsan Tower. The public discovered their true nature. The group disbanded. Five demons — four of whom are still presumably operational, their fates unresolved — are somewhere out there, separated from Gwi-Ma, separated from the structure that defined them for however long they had been demons, and presumably confronting for the first time in a very long time the question of who they are when they are not the Saja Boys.
The sequel cannot come soon enough.
The Saja Boys Voice Cast
Jinu is voiced by Korean actor Ahn Hyo-seop, known for his roles in A Time Called You and Business Proposal. His singing voice is provided by Andrew Choi. Ahn Hyo-seop described the role as an opportunity to explore a character who made a terrible decision out of love and has been paying for it ever since — a character who, despite everything, still holds onto warmth.
The other Saja Boys are voiced by an ensemble of Korean and Korean-American talent whose full credits are embedded in the film's production. The creative team sought voices that could sound young enough to pass as K-pop idols while carrying the weight of characters who are anything but young in the conventional sense — demons who have existed far longer than their appearance suggests, playing at youth as part of a performance that is itself a weapon.
Frequently Asked Questions
Who are all the members of the Saja Boys in K-Pop Demon Hunters? The Saja Boys have five members: Jinu (the leader and main vocalist), Mystery (the main dancer), Romance (the visual), Baby (the maknae and fastest fighter), and Abby (the all-rounder, sometimes credited as Abs). All five are demons in disguise who formed a K-pop boy band on Gwi-Ma's orders to steal fans from HUNTR/X and weaken the Honmoon.
What does the name Saja Boys mean? Saja comes from the Korean word for lion, reflected in the group's lion-themed visual identity. It also references the Jeoseung Saja — supernatural figures from Korean spiritual tradition who guide the souls of the deceased to the afterlife. In the film, this sacred function has been corrupted by Gwi-Ma: his Saja Boys steal the soul energy of living fans rather than guiding the dead peacefully.
What is Jinu's backstory in K-Pop Demon Hunters? Jinu was born in 1600s Joseon-era Korea into deep poverty. He accepted a deal from Gwi-Ma that gave him a powerful singing voice and the wealth to help his family — but it came at the cost of his soul, condemning him to the demon world and separating him from the family he had sacrificed to protect. He has lived for over four hundred years in guilt over that choice, enslaved as much by his own shame as by Gwi-Ma's control.
Does Jinu die in K-Pop Demon Hunters? Jinu sacrifices himself in the film's climax, stepping in front of Gwi-Ma's killing blow to protect Rumi and transferring his restored soul to her to empower HUNTR/X for the final battle. Whether he was destroyed entirely or his soul found peace after the sacrifice is deliberately left ambiguous — a question the confirmed sequel is expected to address.
Why did Jinu betray Rumi at the Idol Awards? Jinu had genuinely planned to help Rumi by sabotaging the Saja Boys' performance at the Idol Awards so HUNTR/X could win and strengthen the Honmoon. Gwi-Ma discovered this plan and forced Jinu back into submission by reminding him of the full truth of what he did to his family four hundred years ago — a shame so consuming that it collapsed Jinu's resolve and forced him back under Gwi-Ma's control.
Will the Saja Boys appear in the K-Pop Demon Hunters sequel? The K-Pop Demon Hunters sequel was officially confirmed in late 2025. Director Maggie Kang has acknowledged that the sequel is naturally set up to explore the other Saja Boys' stories and backstories more deeply — arcs that could not be developed fully in the first film due to runtime constraints. The fandom's expectation is that Mystery, Romance, Baby, and Abby will receive significantly more character development in the sequel.