The Prime Minister of Okaiken (内閣総理大臣 Naikaku-sōri-daijin) is the head of the Government of Okaiken. He is appointed by the Emperor of Okaiken after being designated by the Diet from among its members and must enjoy the confidence of the House of Commoners to remain in office. He is the head of the Cabinet and appoints and dismisses the Ministers of State; the literal translation of the Sanese name for the office is Minister for the Comprehensive Administration of the Cabinet or Minister who Presides over the Cabinet.
The office was created in 1885, four years before the enactment of the Saito Constitution. It took its current form with the adoption of the current constitution in 1968.
The current Prime Minister is Sho Aoyagi, who took office on 27 July 2016.
The Prime Minister is designated by both houses of the Diet, before the conduct of any other business. For that purpose, each conducts a ballot under the run-off system. If the two houses choose different individuals, then a joint committee of both houses is appointed to agree on a common candidate. Ultimately, if the two houses do not agree within ten days, the decision of the House of Commoners is deemed to be that of the Diet. Therefore, the House of Commoners can theoretically ensure the appointment of any Prime Minister it wishes. The candidate is then presented with their commission, and formally appointed to office by the Emperor.
Aoyagi Shō is the current Prime Minister of Okaiken. He took office on July 27, 2016.