Social Democratic Party of Japan (Cherry, Plum, and Chrysanthemum)

The Social Democratic Party of Japan (みょうみ しゃかい みんしゅとう; 明湄社會民主黨 Myōmi Shakai Minshuto) is a Japanese political party founded in 1920. and being the part of the National Front with the Nationalist Party of Japan (MKT) since its foundation.

The Social Democratic Party was originally formed as the Reorganized Social Democratic Party, an attempt to unified all left-minded political parties in Japan into one party and to revive the original Social Democratic Party that established in 1901. The Reorganized SDP was formed through the merger of the right wing of Japanese Socialist Party, Japanese Agrarian Party, the Society for Enlightenment, and the Japanese Fabian Society.

In 1927, during the time of "First Political Consolidation" (1925-1934), the SDP dropped its "Reorganized" title from its official name and renamed itself as the Social Democratic Party of Japan. The Social Democrats together with the Japanese Communist Party represented the left-wing elements of National Front until 1934. The dissolve of Communist Party made the Social Democrats as the only left-wing party in National Front since 1934. Many members of right-wing of Communist Party of Japan joined the Social Democratic Party.

During the "Second Political Consolidation" (1945-1950), many members of the Social Democrats joined the reorganized Nationalist Party of Japan under General Katobushi Toshio. There were many attempts since 1947 to merge the Social Democrats with the Nationalists to establish a new political balance, but its were never came to fruition.