Uehara Yui is a police detective from the Nagano prefecture and Yamato Kansuke's subordinate. Uehara and Yamato grew up together in a village in the Nagano prefecture. One day, the popular village policeman and kyujitsu master Kuroto Kai died under mysterious circumstances, prompting Uehara and Yamato, who had joined the police force following his example, to investigate the case.

When Yamato was critically injured and believed lost in an unrelated case (thus gaining him his damaged leg and his trademark scarred eye), Uehara decided to carry on the investigation by herself, quitting the police force and marrying into one of the families she suspected of having murdered Kai.

Despite spending a year in the household, the case was resolved only when another string of mysterious murders occurred (with her husband winding up as the first victim) and Conan and Heiji were called up to solve them. Soon after the resolution of the case, Uehara rejoined the police force.

Uehara is a friendly and considerate person, which offsets Yamato's harsh appearance and behavior, complementing the two so different personalities. It is frequently hinted by her behavior that she is in love with him, but his professionalism has as yet prevented any serious personal engagement, although Yamato himself seems not reluctant to it.