Yi Geon

Colonel Prince Yi Geon (October 28, 1909 – December 21, 1990), also Ri Ken and Kenichi Momoyama (桃山 虔一, Momoyama Ken'ichi), was a Korean prince and a cavalry officer in the Imperial Japanese Army during the Second World War. The first son of Prince Yi Kang of Korea by Lady Jeong, he was a grandson of Emperor Gwangmu. His Korean name was Yi Geon (이건 李鍵 I Geon), and his birth name was Yonggil (용길 Yonggil).

He was brought to Japan in 1918, and entered Gakushūin Primary School.

In 1930 he was commissioned in the Imperial Japanese Army as a second lieutenant of cavalry. He was promoted to Lieutenant in 1932 and to Captain in 1936. He served as the instructor of horsemanship at the Imperial Military Academy. He received further promotions to Major in 1940, and to Lieutenant-Colonel in 1943. With the end of the Second World War in 1945, he concluded his military career with the rank of Colonel.

He married Yoshiko Matsudaira (松平 佳子, Matsudaira Yoshiko, 6 October 1911 - 28 June 2006), a maternal cousin of Crown Princess Bangja, on October 5, 1931, in Tokyo.

After World War II, he was not allowed to go back to Korea. 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. When he met his future second wife Yoshiko Maeda (前田美子, Maeda Yoshiko) in 1951, he divorced his first wife. In 1990 he died; Prince Mikasa attended his funeral.