Mirumoto Ujino was the brother of the Mirumoto DaimyoMirumoto Watanubo. When his brother died in 805 without a male heir, Ujino claimed the right to lead the Mirumoto family. Watanobu's daughter Mirumoto Kaijuko, who was only sixteen at the time and just one year out of her gempukku, challenged his claim saying; "Only if you can take my life can you take my father's place." Ujino had no wish to kill his niece, but if he backed out he would loose face. They went through with the duel, and Kaijuko soundly beat her uncle. With that, Kaijuko became the first female daimyo of the Mirumoto family and her rule was never questioned again.