Kou Shuurei is the eldest daughter of the Crimson Clan, a sixteen-year-old girl when the story begins. She aspires to become Saiunkoku's first female official in the Imperial Court, and her journey towards her dream and beyond is focused throughout the series.
Shi Ryuuki is the reigning emperor of Saiunkoku and nineteen years old as the story begins. As the youngest of the previous Emperor's six sons, each from a different mother, he had been an unlikely candidate to ascend to the throne. During childhood, Ryuuki was badly treated by his mother and most of his half-brothers, who would beat him and lock him in a storage house for days in a row. Seien was the only member of the family who showed kindness to him. Ryuuki often took refuge in the garden or the imperial archives; in the latter location, he first encountered Shouka Kou, who tutored the young prince and encouraged War General Sou-Taifu to teach him swordsmanship.