As soon as he was enthroned, he allowed many princes to be demoted from nobles to subjects; due to his illness, his son, Emperor Uda (Sadami) was returned as a prince on August 25, Ninna 3 and Emperor Uda became the crown prince on August 26, Ninna 4.
即位と同時に皇子を多く臣籍降下させたが、病を得たため仁和3年8月25日に子宇多天皇（さだみ）を親王に復し、翌8月26日に立太子させた。