The Kenseikai was founded on 10 October1916, as a merger of the Rikken Dōshikai, Chūseikai and the Kōyū Club. Led by Katō Takaaki, the new party was united by its opposition to the policies of the ruling Rikken Seiyūkai under Prime MinisterŌkuma Shigenobu. The party was supported financially by the Mitsubishizaibatsu, due to family ties with Katō Takaaki. Party leaders included Hamaguchi Osachi and Adachi Kenzō. The merger gave the Kenseikai a total of 198 seats in the Lower House of the Diet of Japan, thus forming a majority, and raised the expectation that Katō Takaaki would become the next Prime Minister. However, the position of Prime Minister was a direct appointment from the Emperor per advice provided by the genrō, and in this case, the genrō unexpectedly nominated General Terauchi Masatake instead. In protest, the Kenseikai initiated a no confidence motion, which subsequently dissolved the Diet and led to the political isolation of the Kenseikai for almost a decade. During its period in the opposition, the Kenseikai strongly opposed the Siberian Intervention and pushed for greater rights for labor unions. In the 1924 General Election, the Kenseikai secured 150 seats, making it the largest single party in the Lower House, but without a majority. Katō agreed to form a coalition government with the Rikken Seiyukai, which had 100 seats, and the Kakushin Club, which had 30 seats. This three-party coalition was the first ruling coalition government in Japanese history, and used its majority to focus on domestic political reform and a moderate foreign policy. It pushed strongly for rule under the Meiji Constitution, without influence or control by the genrō. It also favored universal male suffrage and much needed reforms in labor laws and in the economic situation for farmers. However, despite its liberal image, the coalition passed the Peace Preservation Law in 1925. Following Katō's death, the party was led by Wakatsuki Reijirō, but his cabinet was unable to weather the Shōwa financial crisis of 1927. The Kenseikaimerged with the Seiyū Hontō in June 1927 to form the Rikken Minseitō.
