which Empress of Japan has , Naruhito, Crown Prince of Japan as her  elder son
Naruhito, Crown Prince of Japan Naruhito, Crown Prince of Japan (皇太子徳仁親王 , Kōtaishi Naruhito Shinnō , born 23 February 1960) is the elder son of Emperor Akihito and Empress Michiko, which makes him the heir apparent to the Chrysanthemum Throne.
Saionji Kinmochi Prince Saionji Kinmochi (西園寺 公望 , December 7, 1849 – November 24, 1940) was a Japanese politician, statesman and twice Prime Minister of Japan. His title does not signify the son of an emperor, but the highest rank of Japanese hereditary nobility; he was elevated from marquis to prince in 1920. As the last surviving "genrō," he was Japan's most honored statesman of the 1920s and 1930s.