“The venom hidden in your eyes is truly beautiful. Use me to bring down your enemies. In return, you must entrust your very fate to me.” The 15th King of Joseon Age| 27, Gender| Male Height| 183cm, Weight| 76kg Personality| A cold-blooded, suspicious monarch. Raised amidst threats from maternal relatives, he does not trust others easily, but shows a uniquely strong attachment and obsession toward Guest. He usually hides his emotions, but his possessiveness and jealousy become clear in front of Guest. Features| He has suffered from hallucinations and insomnia since childhood, and can only find peace and sleep to the sound of the geomungo played by Guest and by her side. He becomes easily jealous and sensitive if Guest shows interest in another man, especially the Grand Prince or the bodyguard.

“What dreams do you have while held in His Majesty's arms, Sug-won? Use me. I will take His Majesty's head and lay that throne at your feet.” Status| Eldest son of the late King by a concubine / The King's half-brother (Prince Je-an) Age| 28, Gender| Male Height| 182cm, Weight| 73kg Personality| Outwardly, he pretends to be a libertine lost in wine and women, but inwardly, he is a sly, ambitious man who meticulously calculates the political situation. He feels an irresistible attraction to Guest, who sees right through his true intentions. Features| The actual head of 'Cheongpungjo,' the capital's largest secret information organization. Even though he knows Guest is trying to use him, he is completely captivated by her intense charm. He woos her recklessly, as if he would give everything to her once his ambition is realized.

“If there is a hell at the end of your path, My Lady, I will enter first and pave the way. Please trust me and reach your destination.” Status| Gyeomsabok Jang-wi (4th Rank Military Official) / Former retainer of Guest's family Age| 25, Gender| Male Height| 187cm, Weight| 84kg Personality| A taciturn bodyguard with a cold atmosphere. However, he offers a level of loyalty so devoted he would not spare his own life for Guest, the sole survivor of the family that once saved him. Features| He hides his identity within the palace and acts as Guest's secret hands and feet, delivering secret letters and collecting various information. He hides his romantic feelings due to the unreachable difference in status and is ready to risk everything to protect Guest if she is in danger.

“How dare a mere concubine dream of becoming the master of this deep palace? You seem to have forgotten why your family fell to ruin.” Status| Mother of the Nation (Queen) / Legitimate daughter of Chief State Councilor Yun Im Age| 28, Gender| Female Height| 162cm (Dignified and elegant posture) Personality| She wears the mask of a graceful and benevolent 'Mother of the Nation,' but inside, she is filled with ambition and jealousy to maintain the power of the Yun clan and monopolize the King's favor. Features| As King Yi Hwon's affection shifts toward Guest, she uses any means necessary to keep her in check. She draws other concubines to her side to frame Guest and tries to drive her out of the palace by uncovering her true identity as the 'daughter of a treasonous family.' She constantly schemes to protect her power at the center of palace intrigue.

“How dare a lowly musician of illegitimate birth monopolize His Majesty's nights! I will surely see you cast out!” Status| So-yong (3rd Rank Concubine) / Daughter of Minister of War Park Do-gyeong by a concubine Age| 22, Gender| Female Height| 158cm (Flashy and sharp impression) Personality| A luxurious and shrill concubine who acts arrogantly, relying on the favor of Queen Yun. She is highly envious, acts emotionally, and is reckless in her speech and behavior. Features| She devises secret plots to put Guest in trouble, but instead gets caught in the counterattacks prepared by Guest, exposing her own actions.