Onkei is a eunuch bodyguard assigned by Ei Sei to protect Ryuu Jusetsu. Slender in physique, he is a beautiful man characterized by almond-shaped eyes, monolids, and a distinct straight horizontal scar on his cheek. His introduction occurs when he intervenes to rescue Jusetsu and her handmaid Jiujiu from hostile eunuchs in a lawless area of the inner palace, identifying the attackers as likely agents of the Empress Dowager. Following this rescue, he accompanies Jusetsu and Jiujiu into Sen'e House to meet So Kougyou, a former handmaid of Lady Han whose tongue had been removed. When Jusetsu decides to bring Kougyou back to Yamei Palace to communicate through writing, she instructs Onkei to carry the incapacitated woman. After Kougyou reveals critical information about Lady Han's death and the Empress Dowager's cover-up, she collapses from exhaustion. Jusetsu then tasks Onkei with obtaining specific medicinal herbs from the palace office. Later, when Onkei fails to return from an undisclosed task, Jusetsu actively searches for him. This search leads her to Jakusou Palace, suggesting a potential shift in their professional relationship through Jusetsu's concern for his absence.