Rikken Minseitō (Constitutional Democratic Party) (立憲民政党, Rikken Minseitō^?) was one of the main political parties in pre-war Japan. It was also known as simply the ‘Minseitō’. A political party is an organization that seeks to attain political power within a government, usually by participating in electoral campaigns. ...

The Minseitō was founded on 1 June 1927, by the merger of the former Kenseikai with the Seiyu Honto, under the leadership of Hamaguchi Osachi. It viewed the Rikken Seiyukai as its main rival. June 1 is the 152nd day of the year in the Gregorian calendar (153rd in leap years), with 213 days remaining. ... 1927 (MCMXXVII) was a common year starting on Saturday (link will take you to calendar). ... Hamaguchi Osachi (浜口 雄幸 April 1, 1870–August 26, 1931) was a Japanese politician and the 27th Prime Minister of Japan from July 2, 1929 to April 14, 1931. ...

In the 1928 election, the Minseitō won 216 of the 464 seats in the lower house of Diet of Japan, thus becoming the single most important party. Hamaguchi became Prime Minister of Japan in 1929, and in the 1930 election, the party expanded its lead to 273 seats, thus obtaining an absolute majority. During its tenure, it advocated fiscal restraint, a conciliatory foreign policy, and ratified the London Naval Agreement of 1930. However, after Hamaguchi was assassinated by a right-wing fanatic in 1930, second party president Shidehara Kijuro was unable to maintain the party momentum. This article is about the Japanese legislature. ... The Prime Minister of Japan (内閣総理大臣 Naikaku sōri daijin) is the English political nomenclature of the head of government of Japan, although the literal translation is Prime Minister of the Cabinet. ... The London Naval Treaty was an agreement between the United Kingdom, Japan, France, Italy and the United States, signed on April 22, 1930, which aimed to regulate submarine warfare and limited military shipbuilding. ... Shidehara on a 1931 issue of TIME magazine. ...

Hamaguchi's successor, Prime Minister Wakatsuki Reijiro was unable to control the military or to prevent the Manchurian Incident, and his government collapsed in 1931. Wakatsuki Reijirō (若槻 礼次郎 Wakatsuki Reijirō) (March 21, 1866 - November 20, 1949) was a Japanese politician and the 25th and 28th Prime Minister of Japan. ... One aspect of the Manchurian Incident (January 1931) was an engagement of the Imperial Japanese Army with Chinese forces. ...

The Minseitō lost its majority in Diet in the 1932 elections. It was able to recover its majority in the 1936 and 1937 elections only by adopting a more pro-military stance.

On 15 August 1940 the Minseitō voted to dissolve itself into the Imperial Rule Assistance Association as part of Hideki Tojo's efforts to create a single-party state, and thereafter ceased to exist. August 15 is the 227th day of the year in the Gregorian Calendar (228th in leap years), with 138 days remaining. ... 1940 (MCMXL) was a leap year starting on Monday (the link is to a full 1940 calendar). ... The Taisei Yokusankai (Imperial Rule Assistance Association, or Imperial Aid Association) was created in 1940 by Japanese Prime Minister Fumimaro Konoye. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... States in which a single party is constitutionally linked to power (or the provisions of its constitution are currently suspended while a single party rules) are coloured in brown. ...