When he was young, he and his father were snubbed due to their background, but after his father was enthroned in 1068 (Jiryaku 4), he was proclaimed a Shinno (Imperial prince) and became Imperial Prince Sadahito.
幼い時は父子ともに冷遇されたが、治暦4年（1068年）、父帝即位とともに親王宣下を受け貞仁親王となる。