It was written in a Johyobun (memorial to the Emperor) dated November 18, 872 of FUJIWARA no Mototsune, who was then the Minister of the Right and a child of FURIWARA no Nagara, that he was the Yushi of his uncle, late FUJIWARA no Yoshifusa (former Sessho Daijo daijin [Regent and the Grand Minister])
貞観_(日本)14年10月10日_(旧暦)の右大臣藤原基経（藤原長良の子）の上表文に自分が叔父である故藤原良房（元摂政太政大臣）の猶子であったことが記されている。