In the Showa period, the Imperial Family Law was re-issued under the Constitution of Japan, the basic rule of the prohibition of the abdication, prohibition of the adoption, and priority of the male direct Imperial member's succession to the throne, remained the same, there was another regulation added that illegitimate children would not be included to the Imperial family.
昭和時代、日本国憲法の下で皇室典範は再度制定されたが、退位禁止と養子禁止と直系男子への皇位継承優先とする基本性格は変わらず、非嫡出子を皇族としない規定が追加された。