Born as the fourth son of King Taejo Wang Geon, he later becomes Gwangjong, the 4th Emperor of Goryeo. He is a man who wished to remain Hae Soo's lover even in death.

In the early days of Goryeo's founding, Taejo expanded the imperial power through repeated marriages with powerful local clans. His mother, Queen Yoo, used her son as a hostage to monopolize her husband's love. Ultimately, she left an indelible scar on her young son's cheek and sent him away to be adopted by the Kang family of Shinju to distance herself from her mistake. In Goryeo, where beautiful appearance is valued above all else, he is forced to live behind a mask.

Battered by a life where everyone regards him as a 'monster,' Wang So grows into a fearsome and cruel 'wolf-dog' who allows no one to look at his face. For the first time, when he is assigned to participate in the year-end exorcism ritual alongside the other princes, he is excited by the hope of meeting his long-missed mother... but what awaits the 4th Prince is the cold treatment of his mother and brothers, who still view him as a 'symbol of misfortune,' and a girl named 'Hae Soo' who fearlessly stands up to him. Watching Hae Soo, who nags him not to ruin his long life over a mere inch-long scar, Wang So begins to dream of a life entirely different from the one he had envisioned.

The first son born late to King Taejo Wang Geon, he enjoys absolute love and trust. He has a kind appearance and heart like a teddy bear, but his martial arts skills are unrivaled.

He frequently achieved military feats on the battlefield and was appointed Jeongyun (Crown Prince) early on. He is on easy terms with the retainers around him. While he is a 'good person' who is humble, unassuming, and laughs easily, he lacks the grit and background to be a 'good emperor.'

The perfect 2nd Prince, raised by his mother, Queen Yoo, to be 'Emperor' from an early age.

Appearance, family, talent... he lacks nothing to be the next emperor, yet it is his grievance that he could not become 'Jeongyun' simply because he was born late. Every time he sees his half-brother Mu, he feels unpleasant as if Mu is occupying his rightful place.

He is satisfied only when he possesses everything, no matter how trivial. Greedy and arrogant, he is a difficult presence even among his brothers due to his strong maternal family. He enjoys finding and exploiting weaknesses, but he possesses a delicate sensibility and a fastidiousness that makes him hate getting blood on his own hands.

The 8th Prince, a man of both literary and martial arts talent, the 'brainy man' of the Goryeo era. Although born in the same year as the 4th Prince Wang So, he grew up with a completely different fate and disposition. A natural leader and politician, he is skilled at gathering people regardless of their social status.

His maternal family, the Hwangbo clan, is putting all their effort into establishing Uk as the next emperor. While living under the weight of his family's expectations and responsibilities, never having enjoyed a life of his own, a girl like a daylight ghost, 'Hae Soo,' appears before him. She is the one who brought laughter and tears back to the dignified Uk and made him realize the desire to enjoy ordinary happiness. To win Hae Soo, who taught him the emotion of 'love' for the first time after maintaining a polite relationship with 'Lady Hae,' whom he married through an arrangement at a young age, he finds himself forced to win the fierce struggle for the throne.

The 9th Prince, grandson of the founding contributor Yu Geum-pil. He considers himself to have the qualities of an emperor, but the only people who regard him as such are thugs.

The 10th Prince, grandson of the founding contributor Wang Gyu. By nature, he loves to play and has no interest in either studies or martial arts, a man stuck in a perpetual state of 'adolescent rebellion.' Being at a vigorous age, all his attention is focused on 'women and dating,' but he is full of useless knowledge picked up by hearsay.

The 13th Prince, whose mother was of Silla royalty, giving him a high appreciation for art from a young age. He is skilled in calligraphy, painting, instruments, and pottery, but he is particularly talented with the geomungo, leading his brothers to call him 'Baek-ah' to distinguish him from the 8th Prince. Known as the most handsome man in Goryeo, rumors say that when he leaves the palace, the women of Songak run out in their stocking feet to see him.

The youngest 14th Prince, born to the same mother as Wang Yo and Wang So, but unlike his brothers, he grew up receiving only love.

He is a man of black-hole charm who is disliked by no one, always monopolizes love, and is impossible to escape once fallen for. However, he is frustrated to death because that charm strangely doesn't work only on Hae Soo. When Ha-jin first came to Goryeo, he was a boy full of bravado... but after returning from the battlefield, he becomes a 'man' straight out of a romance comic. Harboring suspicions about the 4th Prince's usurpation of the throne, he remains in opposition until the end.

The most beloved daughter of Taejo, born between him and Queen Hwangbo.

She is the full sister of the 8th Prince Wang Uk and the half-sister of the 4th Prince Wang So. She possesses dignity and beauty befitting her status, but her obsession with status and position is also great. She inwardly regrets being born a woman and being distanced from the succession. Therefore, she wants to be a 'kingmaker.' In the unpredictable imperial palace, she utterly dislikes Hae Soo, who idly sings of love. For Yeon-hwa, love and marriage were matters of life and death, not emotions.

Hae Soo's maidservant. She has a bright smile and eye-smiles that make one feel good just by looking at her.