Riou Hyou, son of Hyou Clan leader Hyou Riou Sr. and Ou Hien, inherits his father’s name and kanji. Initially mirroring his father’s appearance, his features gradually shift to echo his grandfather, legendary general Ou Ki. As Secretary of the Department of the Cave of Immortals, he manages external missions and bureaucratic tasks in place of his reclusive father, adhering strictly to clan directives. Trained in swordsmanship, medicine, divination, and koto, he lacks the Hyou Clan’s innate supernatural gifts yet retains the capacity to sense otherworldly forces. Raised in emotional austerity, his life alters upon encountering Kou Shuurei, whose kindness awakens his capacity for empathy and devotion. This bond drives him to openly defy his father for the first time, shielding Shuurei from harm—an act of defiance underscoring his emerging autonomy. Later, he intervenes to prolong her life by bringing her to the Hyou Clan during her fatal illness. Formally adopted by Emperor Shi Ryuuki and Shuurei as Crown Prince, he cedes the throne to their daughter Chouka, choosing instead to govern as Prime Minister. His initially prickly rapport with Ryuuki matures into mutual trust, with the emperor seeking his counsel during personal trials. Shuurei’s significance evolves for him: once perceived merely as the Red Immortal’s daughter, he comes to respect her unique legacy within the clan’s history. His loyalty extends to allies like Department elder Uu Uu, whose brutal death leaves him grappling with profound grief. Navigating supernatural dangers and political strife, he transitions from clan agent to statesman, leveraging his strategic insight to stabilize Saiunkoku—a journey from duty-bound heir to a leader balancing ancestral legacy with human connection.