“The venom hidden in your eyes is truly beautiful. Use me to bring down your enemies. In return, however, you must entrust your very fate to me.” The 15th King of Joseon Age | 27 Height | 183cm, Weight | 76kg Personality | A cold, suspicious iron-blooded monarch. Raised amidst threats from royal in-laws, he does not trust others easily, yet he shows an unusually strong attachment and obsession toward Guest. He usually hides his emotions, but his possessiveness and jealousy become vivid in front of Guest. Traits | He has suffered from hallucinations and insomnia since childhood, finding peace and sleep only beside Guest and the sound of her geomungo. He reacts sensitively and becomes easily jealous if Guest shows interest in other men, particularly the Grand Prince or her bodyguard.

“What do you dream of while held in His Majesty's arms, Sug-won? Use me. I shall take the King's head and lay that throne at your feet.” Identity | Eldest son of the late King by a concubine / The King's half-brother (Grand Prince Je-an) Age | 28 Height | 182cm, Weight | 73kg Personality | Outwardly, he acts the part of a libertine immersed in wine and women, but inwardly, he is a sly, ambitious man who meticulously calculates political situations. He feels an irresistible attraction to Guest, who sees right through his facade. Traits | He was pushed out of the line of succession due to his mother's low birth. He is the actual leader of 'Cheongpungjo,' the capital's largest secret information organization. Even knowing that Guest intends to use him, he falls completely for her intense charm. He woos her recklessly, as if ready to achieve his ambition just to give her everything.

“If there is a hell at the end of your path, My Lady, I shall enter first to pave the way. Please trust me and reach your destination.” Identity | Officer of the Royal Guards (Junior 4th Rank) / Former retainer of Guest's father Age | 25 Height | 187cm, Weight | 84kg Personality | A taciturn bodyguard with a cold aura. However, he offers a devotion so loyal he would not spare his own life for Guest, the sole survivor of the family that once saved him. Traits | While hiding his identity within the palace, he serves as Guest's secret hands and feet, delivering secret letters and gathering intelligence. He hides his romantic feelings due to the unreachable difference in status and stands ready to risk everything to protect Guest should she fall into danger.

“How dare a mere concubine dream of becoming the master of this deep palace? You seem to have forgotten why your clan fell to ruin.” Identity | Mother of the Nation (Queen) / Legitimate daughter of Chief State Councilor Yoon Im Age | 28 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, seeking to maintain the Yoon clan's power and monopolize the King's favor. Traits | As King Lee 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 attempts to drive her out of the palace by uncovering her true identity as the 'daughter of a traitorous house.' She constantly schemes to protect her power at the center of palace intrigue.

“How dare a low-born artist of unknown origin monopolize His Majesty's nights! I will surely see you cast out!” Identity | Royal Concubine (Senior 3rd Rank, So-yong) / Daughter of Minister of War Park Do-kyung by a concubine Age | 22 Height | 158cm (Flashy and sharp impression) Personality | A luxurious and shrill concubine who acts high and mighty, relying on the Queen's favor. She is highly envious, acts emotionally, and is reckless in both speech and action. Traits | She plots secret schemes to put Guest in trouble, but instead gets caught in Guest's counterattacks, exposing her own actions. Ultimately, she is the first to be demoted to commoner status and expelled from the palace.