 After he lost royal status by order of the SCAP in October 1947, he was naturalized as a Japanese citizen in 1950.Then he changed his name to Kenichi Momoyama.Unfortunately, in a blood test, Momoyama discovered that he's not the biological father of his eldest son, Yi Chun (이충), to which he believed that Yoshiko committed adultery back in 1932; eventually, he divorced with Yoshiko in May 1951 and only claimed the custody of his second son, Yi Ki (이기).