Prince Saionji Kimmochi (or Kinmochi) was born into the Takudaijii kuge (Japanese court nobility) and was later adopted by the Saionji kuge. He grew up near the Imperial Palace in Tokyo and was a childhood friend of the emperor Meiji. Saionji participated in politics from an early age, as was expected, given his family lineage.
He was influential in advocating that the Japanese imperial court take part in the Boshin War (1868–69) between the Tokugawa Shogunate and the proimperial forces in Japan. The Tokugawa Shogunate's defeat in this war made the Meiji Restoration possible.
Saionji had more exposure to European ideas than most Japanese of his time: He lived in France for 10 years (1870–80), during which time he took a law degree at the Sorbonne and became friends with many French intellectuals and politicians, including Georges Clemenceau, the authors Edmond de Goncourt and Jules de Goncourt, and Théophile and Judith Louis Gautier.
As a result of his travels, Saionji became more liberal and less nationalistic in his approach to life than many of his Japanese peers, and he advocated the establishment of strong links between Japan and Europe.
Upon his return to Japan in 1881, Saionji founded the newspaper the Oriental Free Press to popularize democratic ideas but abandoned the paper in favor of government service. He served as education minister of Japan under Ito Hirobumi, advocating a liberal and international approach to education, and was influential in the founding of Kyoto University in 1897.
Saionji was one of the cofounders of the Rikken Seiyukai (Friends of Constitutional Government) political party in 1900. He held a number of other government positions over the years, serving in several cabinets, as president of the privy council, and twice as foreign minister. He served as prime minister for two terms, in 1906–08 and 1911–12. In 1919 Saionji was the head of the Japanese delegation to the Paris Peace Conference.
He also served as tutor to Hirohito, grandson of Emperor Meiji, who became emperor on his father's death in 1926 and may be best remembered today for announcing Japan's surrender to the United States in 1945 (ending World War II) and renouncing his claim to divinity in 1946. Saionji remained influential at the Japanese court through his position as a genro, or elder statesman, advising the emperor on political appointments in his cabinet and military leadership.