Baron Kijūrō Shidehara was a pre–World War II Japanese diplomat and politician. He was prime minister of Japan from 1945 to 1946 and a leading proponent of pacifism in Japan before and after World War II. He was the last Japanese Prime Minister who was a member of the peerage (kazoku). His wife, Masako, was the fourth daughter of Iwasaki Yatarō, founder of the Mitsubishi zaibatsu.

The prime minister of Japan is the head of government and the highest political position of Japan. The prime minister chairs the Cabinet of Japan and has the ability to select and dismiss its ministers of state. The prime minister also serves as the commander-in-chief of the Japan Self Defence Forces and is a sitting member of either house of the National Diet. The current prime minister is Fumio Kishida of the Liberal Democratic Party, who assumed the office on 4 October 2021.