10 Love in Disguise Facts, Casting Yim Si Wan Took Nearly a Year

Love in Disguise takes the familiar chaebol romance and deliberately puts it under suspicion.

Starring Yim Si Wan and Seol In Ah, the tvN romantic thriller combines murder investigation, workplace comedy, gender disguise, and an employer-secretary romance while reaching international audiences through Prime Video.

Yoon Yi Jun is a perfectionist third-generation conglomerate heir who becomes a murder suspect, while former special-forces soldier Kang Jae Hee goes undercover as his male personal secretary to investigate him at close range.

He believes his new secretary is a man; she believes her new boss may be a killer.

Behind that deliberately unstable setup was a production that spent unusually long on casting, physical transformation, action preparation, and finding ways to make an old disguise trope feel new.

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1. Casting Yim Si Wan Took Nearly a Year

The leading-man search was not quick. Executive producer Kim Ho Jun said the production spent almost a year navigating the casting process because the role needed an actor who could make Yoon Yi Jun feel recognizably romantic while still creating a type of romance hero audiences had not already seen.

That made Yim Si Wan an intriguing choice. His recent filmography had leaned heavily toward genre projects and darker character work rather than straightforward romantic comedy, which convinced the producers that there was still an unexplored side of him on screen.

Their request was simple but ambitious: build a romance character that did not feel copied from an existing archetype.

2. Yim Si Wan Chose a Brighter Drama After Feeling the Weight of Darker Roles

The timing turned out to suit the actor personally. After playing several intense or villainous characters, Yim Si Wan had begun thinking about how consistently dark roles could affect him emotionally.

By the time Love in Disguise reached him, he was actively interested in something lighter.

He later described romantic-comedy production as emotionally different from playing a villain.

Instead of pushing away affection and warmth to remain inside a darker character, this project allowed him to accept the care, friendliness, and energy surrounding him on set. Once filming wrapped, he felt choosing the drama had been the right decision.

3. Seol In Ah Was Cast Partly Because the Producers Had Already Seen What Her Body Could Do

Kang Jae Hee could not merely look convincing in a suit. As a former special-forces soldier and detective who physically protects the male lead, the character needed an actress capable of making that reversal of the usual romance dynamic believable.

Executive producer Kim Ho Jun said seeing Seol In Ah demonstrate her physical ability on Iron Girls gave him confidence that she could handle Jae Hee.

The production needed someone strong enough for the action while still carrying the emotional qualities of a romantic heroine—an unusually specific combination that made the casting process difficult.

4. The Team Deliberately Tried to Break the Coffee Prince Gender-Disguise Template

One comparison hovered over the project before filming even began: Go Eun Chan, Yoon Eun Hye’s iconic gender-disguise character from Coffee Prince. Rather than avoiding that history, Kim Ho Jun addressed it directly with Seol In Ah.

His challenge was to move away from an archetype that had influenced Korean television for nearly two decades.

The production spent considerable time matching Jae Hee’s physicality and visual design to that goal, aiming for a woman whose disguise worked not because she became delicate or ambiguous, but because her strength and disciplined body language supported the identity she was presenting.

5. Seol In Ah Started Stunt Training Before Production and Kept Working on Her Stamina

The action preparation was substantial enough that Seol In Ah joked Jae Hee could almost have her own action series.

Beginning during pre-production, she spent significant time at a stunt school rehearsing with the action team and coordinating the movements required for the character’s many physical sequences.

She also anticipated a practical problem: once the shooting schedule became busy, regular workouts would become harder to maintain.

Because Jae Hee needed to project physical strength consistently across the drama, Seol In Ah worked heavily on her stamina in advance rather than relying on short bursts of preparation for individual action days.

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6. Her Preparation Went All the Way Down to How Jae Hee Walked and Sat

Learning fight choreography was only the obvious part. Seol In Ah also studied how Jae Hee should physically occupy ordinary spaces when nobody was fighting. She practiced details including the character’s walk and even the way she sat.

That attention matters because the undercover identity has to survive quiet scenes too. A character with a military background cannot suddenly lose that physical discipline when entering an office or sitting across from her suspicious boss.

The performance therefore treats posture as part of the disguise rather than leaving the entire transformation to hair and wardrobe.

7. Yim Si Wan Was Surprised When Seol In Ah Arrived at the Table Read Looking Like a Bodyguard

The transformation became real for Yim Si Wan at the script reading. He knew Seol In Ah had been preparing for the part, but he did not expect her to arrive with short hair and an appearance he immediately associated with a professional bodyguard.

That first impression changed how he imagined the drama. Seeing his co-star already embody the disguise convinced him that Jae Hee’s visual transformation itself could become part of the audience’s fun.

tvN later emphasized that both leads worked closely on details from hairstyles to clothing to strengthen the contrast between their characters.

8. The Leads Ruined Multiple Takes Because They Could Not Stop Laughing

The murder investigation did not make the set particularly grim. Yim Si Wan recalled many moments when he and the cast struggled to hold back laughter, with some takes needing to be filmed again because the performers simply could not stop.

He connected that relaxed atmosphere directly to the comedy in the finished material. Rather than treating the funny scenes as isolated technical exercises, the cast tried to use the energy already circulating between them.

For a drama constantly moving between suspicion and flirtation, that off-camera ease gave the actors a useful counterweight to the thriller mechanics.

9. Kim Jung Hyun Presented the Same Character in Eight Different Tones

Supporting casting produced one of the more unusual preparation stories. Kim Jung Hyun plays Kim Si Hyun, Yi Jun’s longtime friend and lawyer, a character positioned between the drama’s romance, mystery, and male friendship.

The production initially worried about offering him the part because he was accustomed to leading roles.

His response erased that concern. Kim Ho Jun recalled Kim Jung Hyun reading the role in eight different tones and manners during their early meeting, demonstrating how many directions he could take the character.

The producer later praised him for becoming an effective bridge between the romantic storyline and the bromance surrounding Yi Jun.

10. The Thriller Plot Was Designed to Solve a Romantic-Comedy Problem

The murder mystery was not added simply to make the drama look darker in trailers. Kim Ho Jun identified a structural problem he had encountered repeatedly while producing romantic comedies: once the central couple finally gets together, the story can lose momentum.

Love in Disguise was built to resist that drop. By interlocking the romance with a continuing thriller plot, the production could keep generating questions after the emotional relationship began progressing.

For the producer, that mixture gave the series more narrative “weapons” than a romance relying entirely on whether two people would become a couple.

FAQ: Popular Questions About Love in Disguise

How many episodes does Love in Disguise have?

Love in Disguise has 12 episodes, scheduled across its Monday-Tuesday tvN run.

Who directed Love in Disguise?

Love in Disguise was directed by Park Dan Hee and written for television by Moon Soo Jung.

Where can you watch Love in Disguise?

Love in Disguise airs on tvN in South Korea and streams on Prime Video in supported international regions.

Final Thoughts on Love in Disguise

Love in Disguise is built around people who cannot safely present themselves exactly as they are.

Jae Hee hides her identity to uncover the truth, while Yi Jun lives behind a polished public image that may be just as carefully constructed. Romance becomes dangerous because intimacy threatens both performances.

The drama also pushes a familiar K-romance setup in a playful direction by making its heroine the investigator, fighter, and physical protector while its male lead becomes the person under suspicion.

Whether the disguises survive or collapse, share the scene—or character dynamic—you are most excited to watch.