Jia Jiu is a mage of Emperor Weishu's court in Yanjing. She is an academic mage, as there are no known ambient mages in Yanjing or Gyongxe. She operates through beads that hold magical powers and states of being.
In 1039 KF, Jia Jiu meets Evvy and seemingly bonds with the girl over their mutual love of cats, making Evvy trust her. Although Evvy believes that Jia Jiu is respectful of ambient magic, Briar Moss doesn't trust her.
Later, Evvy is taken by Jia Jiu and her soldiers in the name of the emperor. At the mage's orders, Evvy is tortured for information on the whereabouts of Parahan, Soudamini, Rosethorn, and Briar. At first Jia Jiu tries to convince Evvy to just tell her, but later she beats Evvy herself for information. When the girl still does not speak—because of a spell that Evvy had cast on herself—Jia Jiu orders that one of Evvy's cats be brought to the chamber to be tortured and killed in front of the girl. When she comes back, Evvy appears to be dead, and Jia Jiu herself examines the body. Later, Evvy's body disappears, and Jia Jiu hopes that they find her before the emperor finds out.
Luvo later kills Jia Jiu and her soldiers by making the fortress collapse in on itself.