Tadao Casa was appointed a police superintendent of various prefectures, secretary of the Home Ministry and then the Foreign Office. Retired from government service after serving as secretary to Prime Minister Keigo Kiyoura (1924) and entered politics.
Rikken Minseito (Constitutional Democratic Party) was one of the main political parties in pre-war Empire of Japan. It was commonly known as the "Minseito". The party platform was politically and economically more liberal than its major rival, the Rikken Seiyukai, calling for rule by the Diet of Japan rather than bureaucrats or genro, elimination of disparities in wealth, international cooperation, and protection of personal liberties. Its main base of support was the urban middle class, but its principal financial backing was the Mitsubishi zaibatsu.