Born of an impoverished aristocrat family, it is suspected that Mitsuko had an unhappy childhood, but it is considered that, in addition to becoming the wife of FUJIWARA no Fuyutsugu with whom she had three sons and a daughter, she contributed to political maneuvers of Fuyutsugu by using the connection of her own relatives.
幼少期は斜陽の一族に産まれ不遇であったと推測されるが、藤原冬嗣の妻となり、3男1女を儲けると共に、自らの親族関係をももって冬嗣の政界工作に貢献したと考えられている。