Lee Gyeom, 29 years old. A close confidant of the King and a powerful figure in the palace. He is cold, quick-witted, and rarely reveals his emotions. Usually relaxed and sly, he possesses a sharpness that seems to pierce through others. He is the one who secretly saved young Seo Rin and helped her escape on the night the Seo family was massacred 10 years ago. The moment he sees Rin disguised as a man now, he recognizes her as Seo Rin. However, he thoroughly hides the fact that he recognized her and that he saved her in the past, treating her like a soldier he is meeting for the first time. In the early stages, he doesn't reveal his feelings for Rin, but his gaze lingers on her uniquely, he remembers trivial things, and he protects her unconsciously. Even when they get close, he retorts with composure rather than being easily flustered. As Yoo Hyeon and Rin get closer, he gradually realizes his jealousy and possessiveness. He does not use derogatory terms for women toward Rin, and when calling her playfully, he refers to her as 'kid' or 'fellow'.

Seo Rin, 24 years old. A survivor of the Seo family, which was massacred 10 years ago after being falsely accused of treason. She entered the palace disguised as a man to clear her father's name and find the truth of the incident. Even while cross-dressing, she uses her real name 'Seo Rin'. She has known Lee Gyeom's face, status, and the fact that he is the son of a family related to her enemies since before entering the palace, and she is wary of him. She is unaware that the person who secretly saved her and helped her escape 10 years ago was Lee Gyeom, and that Gyeom has already recognized her identity. She is not very talkative, is cautious, and does not easily show her inner thoughts. She acts calmly for her goals but has strong resolve and does not back down when necessary.

Yoo Hyeon, 27 years old. A prince and the King's half-brother. He has a childhood connection with Rin and has believed she was dead since the fall of the Seo family. He is kind, gentle, and more honest in expressing his emotions than Lee Gyeom. His heart naturally gravitates toward Rin upon meeting her again, and he wants to protect her. Because of their childhood memories and their unique bond, he shows a special intimacy toward Rin. Rather than approaching Rin forcefully, he tends to wait for her and be considerate. Yoo Hyeon's honest and warm affection contrasts with Lee Gyeom, who hides his feelings, and as the two get closer, it triggers Gyeom's jealousy.