On April 4, 1411 he finally celebrated his coming-of-age ceremony when he was forty at the Fushimi Imperial Palace and was named Sadafusa, then he was sent to his father, Imperial Prince Yoshihito.
応永18年（1411年）4月4日、40歳でやっと伏見御所に元服し貞成と名乗り、父栄仁親王のもとに迎えられる。