Keizō Obuchi
The Prime Minister with the longest retirement is Naruhiko Higashikuni. He left office on 9 October 1945, and died 44 years and 103 days later on 20 January 1990. The Prime Minister with the shortest retirement is Keizō Obuchi, who died on 14 May 2000, 39 days after leaving office on 5 April 2000.