Election of the Prime Minister of Japan

The Japanese political system has three types of elections: general elections to the House of Representatives held every four years (unless the lower house is dissolved earlier), elections to the House of Councillors held every three years to choose one-half of its members, and local elections held every four years for offices in prefectures, cities, and villages. Elections are supervised by election committees at each administrative level under the general direction of the Central Election Administration Committee, an attached organization to the Ministry of Internal Affairs and Communications (MIC). The minimum voting age in Japan's non-compulsory electoral system was reduced from twenty to eighteen years in June 2016. Voters must satisfy a three-month residency requirement before being allowed to cast a ballot.

For those seeking office, there are two sets of age requirements: twenty-five years of age for admission to the House of Representatives and most local offices, and thirty years of age for admission to the House of Councillors and the prefectural governorship. Each deposit for candidacy is 3 million yen (30 thousand dollars) for single-seat constituency and 6 million yen (60 thousand dollars) for proportional representation.

The National Diet (Kokkai) has two chambers. The House of Representatives (Shugi-in) has 475 members, elected for a four-year term, 295 members in single-seat constituencies and 180 members by proportional representation in 11 block districts. In this system, each voter votes twice, once for a candidate in the local constituency, and once for a party, each of which has a list of candidates for each block district. The local constituencies are decided by plurality, and the block seats are then handed out to party lists proportionally (by the D'Hondt method) to their share of the vote. Often the parties assign the block list spots to single-seat candidates, so that unsuccessful single-seat candidates have a chance to be elected in the proportional block. Parties may also place dual district and block candidates on the same list rank; in that case, the Sekihairitsu system determines the order of candidates. General elections of members of the House of Representatives (Shūgiin giin sō-senkyo) are usually held before the end of a four-year term as the chamber may be dissolved by the cabinet (via the Emperor). Most prime ministers use that option. The only exception in post-war history was the "Lockheed election" of 1976 in which the Liberal Democratic Party lost its seat majority for the first time.

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