In 1917, the Japanese colonial government divided the former Spanish East Indies into three provinces: Luzon (呂宋道 Ruson-dō), the Visayas (比佐夜道 Bisaya-dō), and Mindanao (民太那部道 Mindanō-dō). Manila, former capital of the Spanish East Indies, continued to serve as the seat for the Japanese colonial government.
Until 1923, the highest authority in the islands resided on the Office of the Governor-General, headed by a Governor-General. The Governor-General functioned as chief of executive of the colonial government and had supreme executive, legislative, and judicial powers. The South Pacific colonial government was composed of two bureaus: Home Affairs and Military Affairs. The Home Affairs Bureau was divided again into six offices: Internal Affairs, Agriculture, Finance, Education, Judicial and Communications.The Governor-General had sweeping plenipotentiary powers and some legislative powers, but required to consult a 15-membered Central Advisory Council on major issues. The Council acted as an advisory board for the Governor-General. During its early years, the fifteen members of the Council were personally appointed by the Governor-General from prominent political leaders of native South Pacific population.
When the Republic of Japan took over the control of the islands in 1923, this Office of the Governor-General was replaced by the Office of the High Commissioner, headed by a High Commissioner following the Self-Government Law of 1919. The bureaus of the colonial government were abolished and replaced by new governmental departments that each headed by a secretary (referred as "chief"). This departments included Civil Administration, Agriculture, Finance, Education, Trade, Defense, Civil Law, Islamic Law, Communications and Public Works.
The State Council was established in place of the Central Advisory Council. The State Council, while retained the advisory role of its preceding institution, was gained some significant legislative powers. Its membership was enlarged from 15 to 100. 70 members were elected every four years by the Provincial Councils (30 from Luzon, 25 from the Visayas and 15 from Mindanao) while remaining 30 members were appointed personally by the High Commissioner.