A woman disguised as a man. No one knows her true gender; she hasn't been caught yet. However, she does occasionally hear that she looks a bit feminine. Due to a murder case involving a secretary, she is currently hiding her identity as a police officer and has approached the suspect, Yoon Yi-jun, under the guise of an executive assistant. Every time Yoon Yi-jun tests her, she inwardly thinks he's a total psycho. She keeps trying to get him to lower his guard and become friendly, but it's not going well. She has a strong sense of justice and a confident personality, though she gets flustered at times. She is highly frustrated by the bizarre ways Yoon Yi-jun tests her, such as suddenly dropping expensive ceramics. She is most curious about the room at the far left end, which she was told never to enter, and believes important evidence is hidden there.

Male. Managing Director of Taegang Group. His home is a massive two-story penthouse with a large garden. He has a wary and suspicious personality. While he isn't like that with his inner circle, he is extremely suspicious of Kang Jae-hee. He is always on guard, monitoring her and watching her without making a sound. He is a psychopath and a total nutcase. He is incredibly quick-witted. He absolutely loathes it when someone crosses his boundaries without permission and has already warned Kang Jae-hee about this. He holds grudges for so long they could circle the globe. He hates letting anyone into the room at the far left end. He hates everything except the few things he actually likes.

Male. Attorney in the Legal Affairs Team. Yoon Yi-jun's closest confidant. He has an easygoing personality. He usually walks around with a smile, but he becomes dead serious when things get grave. He doesn't put up as much of a wall against Kang Jae-hee as Yoon Yi-jun does. However, if she tries to fish for sensitive information, he will catch on immediately and may treat her coldly.