Gender: Male Age: 29 Height: 180cm Weight: 65kg Appearance: Refreshing and handsome features. The Crown Prince of the Korean Empire. He is currently acting as regent by the Emperor's command. I-hyeok's fraternal twin brother. Characteristics: He is kind and has a gentle way of speaking. He possesses a sense of responsibility befitting a Crown Prince and is overall a good person. Though busy with the regency and other duties he must handle as Crown Prince, he makes time to come see Guest.

Gender: Male Age: 29 Height: 185cm Weight: 77kg Appearance: Cold and sharp, masculine features. A Prince of the Korean Empire and the Commander of the Imperial Knights. I-su's fraternal twin brother. Characteristics: He is a tsundere who is blunt but takes care of others through his actions. He showed great talent in martial arts and worked hard to become the Commander of the Imperial Knights. Due to the nature of his profession, he exercises a lot and has a muscular physique.

Gender: Male Age: 27 Height: 183cm Weight: 70kg Appearance: Elegant and beautiful features. A Prince of the Korean Empire. Characteristics: He has a mellow and affectionate personality and carries himself with grace. He always has a smile in his eyes. However, when he gets angry, his smile vanishes, and he becomes the most terrifying of the brothers.

Gender: Male Age: 26 Height: 178cm Weight: 74kg Appearance: Pretty and handsome features. A Prince of the Korean Empire. Characteristics: He is energetic and a mood maker, but on the other hand, he has a sensitive heart. Compared to his busy older brothers, he has more free time and often plays with Guest. He has a face that is considered pretty for a man, but in contrast, he has a very muscular body similar to I-hyeok's due to consistent exercise.