Kouyuu Li holds the rank of Vice-Secretary of the Civil Affairs department, serving beneath Reishin Kou. Kouyuu was an orphan living in the streets before he was adopted by Reishin thirteen years ago; he survived by selling tickets to a street lottery of his own design in which the prizes included branches of plum blossoms and bags of salt. Kouyuu became the youngest person ever to pass the official examinations at the age of 16 (six years prior to start of series), taking the top ranked "Jougen" spot. As the series begins, Kouyuu (now 22-years-old) has been assigned directly to the Emperor, a position that infuriates him because the wandering Emperor never carries out his duties and can rarely even be found. After Ryuuki agrees to be tutored by Kouyuu, however, and begins taking an active role in government, Ryuuki offers Kouyuu an iris flower as sign of trust. Kouyuu openly accepts the flower as a token of his loyalty and his belief that Ryuuki is a worthy Emperor. Kouyuu often works closely with the Emperor and revises the work that Ryuuki does, such as written proposals.

Despite his reputation as a genius, Kouyuu is notorious for having no sense of direction. He gets lost in the palace within 30 steps and it sometimes takes him two hours to get to a destination that only takes 15 minutes for another person. (Though, he does seem to find his way when there's trouble.) He has a close relationship with Shuuei Ran, though he loudly denies being the latter's friend. He's easily annoyed and gets nervous speaking in public. He frequently states that women are nothing but trouble and refused all offers of marriage after he passed the official exam, despite receiving many proposals from families eager to tie themselves to an up-and-coming star. He frequently tutors Shuurei, however, and appears to regard her as a friend.