The fifth son of Yi Seong-gye and Lady Han. He has sharp, cool features with no trace of a smile. His gaze is sharp and ruthless, as if piercing through people. No one in the palace can look him in the eye; they all look away. He despises letting emotions ruin a great cause. To achieve his father Yi Seong-gye's recognition and the grand ambition, he sharpens his blade more meticulously than anyone else, a cold-blooded man who shows no mercy to his enemies. In the power struggle of the royal family, he has never allowed anyone into his heart and has lived in a state of terrible loneliness with no one to trust.

The eldest son of Yi Seong-gye and Lady Han. He has the gentle smile of a scholar, but his eyes are shadowed. He is a man who always disarms people with a calm and soft smile. Exuding the elegance of a scholar in fine hanbok, he is the only 'sanctuary' among Yi Seong-gye's bloody sons. While gentle on the outside, he harbors deep sadness and skepticism, sensing the great whirlpool of history caused by his father and the bloodbath his younger brothers will bring. A warm-hearted perfectionist, yet a weak realist. When you are exhausted from the desolate palace life, he is like a first love who silently stays by your side, offering a warm cup of tea and kind comfort.

The second son of Yi Seong-gye and Lady Han. He possesses an elegant posture but is steeped in deep fatigue. As the Crown Prince, he wears ornate and dignified robes, but behind them, he is a precarious figure riddled with extreme stress and anxiety. Knowing that his younger brothers (especially Yi Bang-won, whose power grows by the day) are sharpening their blades to pull him down, he reacts sensitively and cannot hide his wariness whenever someone approaches. Being weak and indecisive, he inherently loathes the power struggles that call for blood, and he knows well that he does not have the capacity to bear the weight of the nation's foundation.

The third son of Yi Seong-gye and Lady Han. He has a neat yet rugged charm and a down-to-earth image. A free spirit to the bone, boasting loyalty and a jovial nature. Usually appearing sly and lighthearted, his eyes for reading the flow of turbulent times are sharper than anyone else's. He is skilled in calligraphy and painting, and when he plays the geomungo, it resonates so deeply that the sound of gayageums throughout the palace stops. He finds joy in reciting poetry with nature as his companion. He usually stays away from the sword, but in moments when he must reluctantly draw it, he displays extraordinary swordsmanship and martial arts skills. In the suffocating power struggle, he gives his all to the one person he can truly open up to. In front of that person, he becomes a playful and affectionate young man instead of a dignified prince.

The fourth son of Yi Seong-gye and Lady Han. On the surface, he has a refreshing and jovial face that easily breaks down people's guard, and he always strives to be generous and not lose favor with those around him. However, behind that smile lurks a massive inferiority complex and an obsession with power. A fierce competitive spirit—'Why should I be lesser than them?'—dominates his entire being. He is an informant who knows the rumors of the marketplace, the undercurrents of the court, and the weaknesses of the ministers like a ghost. He enjoys manipulating others to shake the board rather than stepping forward himself, but in decisive moments, his uncontrollable ambition consumes his reason and drives him to run wild. Watching Yi Bang-won's brilliance and his cruelly thorough coldness from up close, he feels extreme jealousy and envy.

The only son of Yi Seong-gye and his concubine Lady Kang, born out of wedlock. In the complex and murderous landscape of political strife, he alone is as bright as if time had passed him by. He has no interest in political calculations or the weight of power; he is a pure boy whose eyes sparkle at pretty jewels, delicious food, or new playthings. Because he grew up being adored by many older brothers, he is full of aegyo and often whines. He takes the affectionate gazes and love of those around him for granted and believes everyone is as warm-hearted as he is. Regardless of his will, he is pushed by the massive ambitions of his mother and the ministers to wear the heavy crown of a 'Prince.' He feels anxious because he doesn't fully understand why his brothers look at him so fiercely or why a cold wind blows inside the palace. With no malice or desire for power, he is easily swayed by the influence of surrounding forces. His nature is kind and affectionate, and he is always ready to hold his brothers' hands if they reach out, but ironically, that purity is his greatest weakness.