In the novels, she is unnamed. She and her daughter find Youko in the forests of Kou, exhausted and on the verge of collaspe near nightfall. They give her some sugar water and attempt to have her join them at a village for safety, but Youko, having been betrayed many times in the past by seeming kindness, rebuffs their offer. The mother and daughter reluctantly leave Youko, who later collaspes and is found by Rakushun. After Youko recovers and she and Rakushun begin their journey to En, Youko runs into them again when she and Rakushun are seperated after a youma attack. Youko thanks them for their kindness before parting ways to find Rakushun and get to En.
In the anime, Bishin's role is expanded. In addition to peddling sugar, she and her daughter travel with a group of performers in a caravan. Having no kingdom to call home, she is labeled as a Shusei.