Ichirō Hatoyama in the context of "Democratic Party (Japan, 1954)"

The Liberal Democratic Party (LDP; Japanese: 自由民主党, romanized: Jiyū-Minshutō), also known as Jimintō (自民党), is a major conservative and nationalist political party in Japan. Since its foundation in 1955, the LDP has been in power almost continuously—a period called the 1955 System—except from 1993 to 1996, and again from 2009 to 2012.

The LDP was formed in 1955 as a merger of two conservative parties, the Liberal Party and the Japan Democratic Party, and was initially led by prime minister Ichirō Hatoyama. The LDP supported Japan's alliance with the United States and fostered close links between Japanese business and government, playing a major role in the country's economic miracle from the 1960s to early 1970s and subsequent stability under prime ministers including Hayato Ikeda, Eisaku Satō, Kakuei Tanaka, Takeo Fukuda, and Yasuhiro Nakasone. Scandals and economic difficulties led to the LDP losing power in 1993 and 1994, and governing under a non-LDP prime minister from 1994 before regaining power in 1996. In 1999, the LDP entered into a coalition with Komeito.

The Japan Democratic Party (日本民主党, Nihon Minshutō) was a conservative political party in Japan. Existing from 1954 to 1955, the party was founded by Ichirō Hatoyama, former foreign minister Mamoru Shigemitsu and future Prime Minister Nobusuke Kishi. The party was formed on 24 November 1954, by merging Ichiro Hatoyama's group which left the Liberal Party in 1953, and the Shigemitsu-led Kaishintō party. On 15 November 1955, the Japan Democrats merged with the Liberals to form the modern Liberal Democratic Party.

Tanzan Ishibashi (石橋 湛山, Ishibashi Tanzan; 25 September 1884 – 25 April 1973) was a Japanese journalist and politician who served as prime minister of Japan from 1956 to 1957.

Born in Tokyo, Ishibashi became a journalist after graduating from Waseda University in 1907. In 1911, he joined the Tōyō Keizai Shimpo ("Eastern Economic Journal") and served as its editor-in-chief from 1925 to 1946 and president from 1941. In the 1930s, Ishibashi was one of the few critics of Japanese imperialism, and became well known as a liberal economist. From 1946 to 1947, Ishibashi served as finance minister under Shigeru Yoshida. He was elected into the National Diet in 1947, but was purged for openly opposing the U.S. occupation policies; he returned to the Diet in 1952, after which he allied with Ichiro Hatoyama and served as his minister of international trade and industry. Ishibashi succeeded Hatoyama as prime minister in 1956, simultaneously serving as director of the Defense Agency, but resigned soon after due to ill health.