Colonel Prince Yi U (Korean: 이우; 15 November 1912 – 7 August 1945) was a member of the imperial family of Korea as a prince, the 4th head[clarification needed] of Unhyeon Palace, and a lieutenant colonel in the Imperial Japanese Army during World War II.

This made him the favorite son of his father, Prince Kang, who himself attempted to escape from Korea to join the exiled Korean government.

He overcame all attempts by the Japanese to marry him off to a minor Japanese noble, [citation needed] and married Lady Park Chan-ju of the Bannam Park clan, a granddaughter of Marquis Pak Yung-hio who was a husband of Princess Yŏnghye of Korea.

[citation needed] Prince U was transferred to Hiroshima in 1945, and on 6 August 1945, he was mortally injured by the atomic bomb blast on the way to his office, and died later that day at a medical aid station.

[1] On August 8, Adjutant Lieutenant Colonel Yoshinari Hiroshi (吉成 弘) committed suicide on account of not being able to save Prince Yi.