Riyou (梨耀), known also as Suibikun (翠微君, Lady Suibi), is the mistress of the Bluemist Aerie (麦州宰, Suibi Cavern) in the kingdom of Sai. She is a flying sage (hisen), a sennin, she has been granted immortality, but does not participate in government affairs. Instead, she lives in the mountains and employs many servants, who are also granted the status of sennin, including Suzu. During the hundred years that Suzu serves her, Riyou is particularly abusive towards Suzu. A woman who expresses unfailing confidence in herself and superiority over others, Riyou is highly astute in her observations of others.
Before becoming a sennin, Riyou had been the favoured concubine of Fu-ou (the Levy-King), who preceeded the two most immediate rulers of Sai, Shishou and Kouko. She had actually greatly aided him in his rule, punishing ministers who had taken advantage of his leniency on the king's behalf and accepting the hate that he would have received for herself. When the king lost the way, she openly censured him. For Riyou's efforts, she had been granted the Bluemist Aerie and received the status of a sennin. Ministers found that she had too much power in the court to be disposed, so they removed her from influencing the king and she was exiled to the Bluemist Aerie. The king swiftly tilted towards ruin soon afterward.
Left to her own devices after her exile, Riyo became extremely bored with her life. Her bitterness toward the world was expressed in how she would cruelly abuse her servants, who were all too meek to stand up to her. Her behavior eventually draws the attention of Kouko after Suzu escapes the Bluemist Aerie. Though Kouko threatens to revoke Riyo's sagehood, Riyo does not rise to Kouko's threat and counters that Suzu's fear of being unable to speak the language of the Twelve Kingdoms does not guarantee that Suzu will be understood or be able to understand others. While Kouko removes all of Riyou's servants and places them in her service, she reluctantly reveals that she agreed with Riyou's statement regarding Suzu when she tells Suzu to travel on her own instead bringing her into the palace as well.