Yi Geon

Colonel Prince Yi Geon (October 28, 1909 – December 21, 1990), also Ri Ken and Kenichi Momoyama (桃山 虔一), was a Korean prince and a cavalry officer in the Imperial Japanese Army during World War II.

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), and his birth name was Yong-gil (용길).

Yi Geon was born on October 28, 1909, at Sadong Palace in Gwaninbang, central Hanseong.

He was the eldest, illegitimate, son of Yi Kang, Prince Uihwa with Lady Jeong of Sugwandang Hall.

His mother was one of the many concubines his father had a relation with.

According to the decree of Emperor Meiji promulgated at the time of the annexation of Korea in 1910, only eight people: Yi Hui, Gojong of Korea, Yi Cheok, Sunjong of Korea, Yun Jeung-sun, Empress Sunjeong, Yi Eun, King Yeongchin, Yi Kang, King Uichin, Kim Suk, Queen Uichin, Yi Jae-myeon, King Heungchin, and Queen Heungchin; were granted a new status as royal family members.

The remaining members of the royal family were also granted a new status, but not grand as their relatives and it was not officially included in the decree.

He graduated from Gyeongseong Kindergarten in June 1916 and entered Ilchul Elementary School on April 6, 1917.

That same year Yi Geon’s younger half-brother, Yi Woo, was adopted by Yi Jun-yong in 1917, followed by a few adoptions of his half siblings, and inherited the throne.

Which created a situation where the younger brother was a part of the royal family but the older brother was not.

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

Another source says that in 1921, Yi Geon was sent to Japan under the pretext of studying abroad and entered the elementary school where he graduated from the school in March 1923.

Yi Geon was arbitrarily given the title of 'Confucius' (공자, 公子) after studying in Japan.

His birth name was Yong-gil (용길, 勇吉), but he changed his name to Geon (건, 鍵) on March 17, 1924.

He was soon officially recognized as a member of the royal family only after the "Wang Gongga Gwebeom" (왕공가궤범, 王公家軌範) was promulgated in 1926.

He was given the honorific title ‘Your Majesty’ (전하, 殿下), which was only used for him.

In April of the same year, he entered the Army Youth School.

According to Article 59 of the 《Wanggonggawebeom》 (王公家軌範), which was enacted and promulgated as Japanese Imperial Ordinance No. 17, on December 1, 1926, to regulate the imperial family of the Korean Empire after the annexation.

It stated that it was mandatory for the king, crown prince, prince royal, and the duke to be commissioned as military attachés in the army or navy after reaching the age of 18.

His half-uncle, Yunghui of Korea, also died on April 25, 1926, as the last “emperor” of Korea.

He was then enlisted to be Jongcheok jibsa (종척집사, 宗戚執事) and led the funeral ceremony.

On May 5, he was permanently appointed the rank.

On June 12, 1930, his father, Yi Kang, went into seclusion and inherited the throne, becoming the new owner of Sadong Palace and was now being called ‘His Highness, the Duke’ (공 전하).

Yi Geon graduated the academy in July 1930.

He married Yoshiko Matsudaira, a maternal cousin of Princess Masako of Nashimoto and member of the Matsudaira clan, on October 5, 1931, in Tokyo.

Yoshiko was a half-sister to Count Tadamitsu Hirohashi, a relative on her mother's side, and changed her name to Seiko Hirohashi.

After she married Yi Geon, she was called Duchess Consort of Yi Geon, Yi Seiko (이건공비 이세이코, 李誠子).

Their marriage raises a few questions or curiosities due to the differences in personalities; Seiko was sociable, while Geon had a quiet personality.

But they eventually had two sons and a daughter.

On October 25, he was commissioned in the Imperial Japanese Army as a second lieutenant of cavalry, and was assigned to the Guards Cavalry Regiment.

Yi Geon was promoted to Lieutenant in 1932 and graduated from the Army Cavalry School in July 1933 where he was later promoted to cavalry lieutenant in August that same year.

He was soon appointed as an instructor at the Military Academy on March 15, 1935, and promoted to Captain on August 1, 1936.

Yi later graduated from the University on December 8, 1938.

From the university, besides Yi Geon, the only Koreans to have graduated there during the Japanese colonial period were Yi Eun, Yi Woo, and Hong Sa-ik.

Two days later, he was appointed as company commander of the Guards Cavalry Regiment.

A year later, on September 13, 1939, he was transferred to the Military University Research Department as an instructor of horsemanship and military instructor for the Imperial Military Academy.

Yi Geon entered the art department as a member of the 42nd class of the Japanese Military Academy.

That same year on Deception 17th, Yi Geon entered the Japanese Army University as its 51st student.

On December 28, in connection with his admission to the University, Yi was transferred from being a horse riding instructor at the Military Academy to a member of the Guard Cavalry Regiment once again.