|Novel||Moribito II: Guardian of the Darkness|
Yuka Yonsa is doctor from Kanbal, and the paternal aunt of Balsa. She is a member of the Yonsa clan.
Yuka is the younger sister of Karuna, the father of Balsa. Described as being even more intelligent than her brother, she had aspired to become a doctor like Karuna and had hoped to go to the capital of Kanbal to study medicine.
After Karuna's wife died, Yuka helped care for Balsa while Karuna served as the king's physician. When Karuna was coerced into poisoning the king so the king's brother could take the throne, Karuna became aware that his family was in danger. After requesting for Jiguro to spirit Balsa away, Karuna lied about his daughter's disappearance in order to protect Yuka and the rest of his family from suffering the consequences of being involved with the king's poisoning. Yuka believed for years that Balsa had been swept away after falling into a river and her body could not be found.
Yuka eventually established a house of healing in the Yonsa clan's lands, where she became a doctor. Years later, she would be one of the few people who recognized Balsa when she returned to Kanbal and would finally learn the truth behind Karuna's death and her niece's disappearance.