Francis Yi Ku (December 29, 1931 July 16, 2005) was a Korean prince who was head of the House of Yi from 1970 until 2005. He was a grandson of Emperor Gojong of the Joseon dynasty. Through Kuni Asahiko, Ku was a second-cousin to Emperor Emeritus Akihito of Japan. Early life Ku was born in Kitashirakawa Palace (which is currently the Akasaka Prince Classic House, formerly part of the Akasaka Prince Hotel), Kioicho, Kojimachiku, Tokyo, Japan; his parents were Crown Prince Yi Un of Korea and Yi Bangja. Ku attended the Gakushuin Peers' School in Tokyo. He later attended Centre College, Danville, Kentucky and studied architecture at Massachusetts Institute of Technology both in the U.S. Adult life He was employed as an architect with I.M. Pei & Assocs, Manhattan, New York from 1959 to 1964. Made stateless by Japan in 1947, Ku acquired United States citizenship in 1959 and Korean citizenship in 1964. He married Julia Mullock (b. 1927) on 25 October 1959 at St George's Church in New York and they adopted a daughter, Eugenia Unsuk. After the fall of Syngman Rhee, he returned to Korea in 1963 with the help of the new president Park Chung-hee, moving into the New Building of Nakseonjae hall, Changdeok Palace with his mother and wife. He lectured on architecture at Seoul National University and Yonsei University and also managed his own airline, Shinhan. When that went bankrupt in 1979, he went to Japan to earn money. In 1982, his family forced him to divorce his wife because she was sterile; his mother died in 1989. He started living with a Japanese astrologer, Mrs. Arita. In November 1996, he decided to reside permanently in Korea. Death Restlessly going back and forth between Japan and Korea, he eventually died of a heart attack, at the age of seventy-five, on July 16, 2005 at the Akasaka Prince Hotel, the former residence of his parents in Tokyo, Japan. His funeral was held on July 24, 2005 and his posthumous title decided as "Prince Imperial Hoeun" () by the Jeonju Lee Royal Family Association. He is buried at the Hoeinwon Royal Tomb near his father and mother. Yi Ku didn't have an heir. According to the Jeonju Lee Royal Family Association, Yi Won, Yi Ku's first cousin once removed, was appointed as the heir by him. Yi Ku already considered adopting an heir for the imperial line