Yoshiko entered the Imperial Court after the death of her father, Nagara, married FUJIWARA no Ujimune, and adopted Emperor Koko's son, MINAMOTO no Sadami, who later became Emperor Uda.
父長良の没後宮廷に出仕し、藤原氏宗と結婚、また光孝天皇の皇子源定省（後の宇多天皇）を猶子とした。