Ryuuki Shi is the reigning emperor of Saiunkoku. He is nineteen years old when the story begins. The youngest of six brothers, he was an unlikely candidate to ascend to the throne. Of his five elder brothers, four killed each other over the succession and one was exiled for treason. As a child, Ryuuki was badly mistreated by his mother and his brothers, except for his brother Seien, who seemed to be the only one who truly cared for him. His other brothers and mother used to beat Ryuuki and lock him in a closet for hours at a time, telling him his birth order was bad and that he stole affection from his siblings. These experiences led to a lingering fear of the dark and sleeping alone. Ryuuki often took refuge in the garden or the imperial archives, where he first encountered Shouka Kou. Shouka tutored the young prince and encouraged War General Taifu Sou to teach him swordsmanship.
Due to his father's dying wish, Ryuuki ultimately rose to the throne. However, he avoided any involvement in politics or government, wandering the palace for hours so no one would be able to find him. He even spread rumors that he preferred the company of men to fuel speculation he could not produce an heir. Ryuuki secretly hoped that Seien, his beloved older brother, would eventually return and take his place as Emperor. Ryuuki's avoidance of responsibility came to an end when he met Shuurei, who told him of her dreams of making a better life for the nation's people. Ryuuki decided to take on his responsibilities and become a respectable Emperor.