Elections in Japan

The Japanese political process has two types of elections.

National Diet
Subnational/local elections

While the national level features a parliamentary system of government where the head of government is elected indirectly by the legislature, prefectures and municipalities employ a presidential system where chief executives and legislative assemblies are directly elected, independently from each other. Many of the prefectural and municipal elections are held together in unified local elections since 1947, held in years before leap years; but since each election cycle of every chief executive or assembly of any prefecture or municipality is independent and not reset after resignations/deaths/recalls/no-confidence votes/dissolutions/municipal mergers, there are also many non-unified local elections today. Prefectural and municipal assemblies are unicameral, the National Diet is bicameral, with the two houses on independent election cycles.

Rules and regulations, supervision

Both national & local elections are regulated by the Public Offices Election Law of 1950.
Elections are supervised by Election Administration Commissions at each administrative level under the general direction of the Central Election Management Council, an extraordinary organ attached to the Ministry of Internal Affairs and Communications. The minimum voting age in Japan's non-compulsory electoral system was reduced from 20 to 18 years in June 2016. Voters must satisfy a three-month residency requirement before being allowed to cast a ballot.
For those seeking offices, 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 for national election is 3 million yen for a single-seat constituency and 6 million yen for proportional representation.

National elections

National elections include:

General elections of members of the House of Representatives, held every four years unless the lower house is dissolved earlier to elect all members of the House of Representatives at once.
Regular/Ordinary elections of members of the House of Councillors, held every three years in staggered elections to six-year terms with half of the membership up in each class.
By-elections of members of the House of Representatives/House of Councillors to fill vacant majoritarian seats
Repeat elections of members of the House of Representatives/House of Councillors after an election has been invalidated, e.g. by a winner missing the legal vote quorum or after election law violations

Japan's post-WWII national legislature, the National Diet, has two directly elected chambers, elected on independent electoral cycles:

House of Representatives

The House of Representatives has 465 members, elected for a rarely completed four-year term, 289 members in single-seat constituencies and 176 members by proportional representation in 11 regional "block" constituencies.
General elections of members of the House of Representatives 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.
The single-seat constituencies are decided by plurality, and the proportional seats are handed out in each "block" constituency to party lists proportionally to their share of the vote. Each voter votes twice, once for a candidate in the local constituency, and once for a party in the regional "block" constituency. In a parallel system, there is no link between votes in one tier and seat numbers in the other; but so-called dual candidacies of one candidate in both tiers simultaneously are allowed. If such dual candidates lose in the majoritarian tier, they still 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 system determines the order of candidates.

House of Councillors

The House of Councillors has 245 members, elected for a fixed six-year term, 147 members by single non-transferable vote in 45 single- and multi-seat constituencies and 98 by proportional representation with optionally open lists in a single, nationwide constituency.
Regular/Ordinary elections of members of the House of Councillors are held once every three years. In staggered elections, half of the House of Councillors comes up for election every three years in elections. The term is fixed, the House of Councillors cannot be dissolved. This, too, is a parallel electoral system. Dual candidacies are not allowed. As in House of Representatives elections, voters have two votes: In the majoritarian election, the vote has to be for a candidate, but in the proportional election, the vote may be for either a party list or a single candidate; in the latter case, the vote counts as both a vote for the party list, and as a preference vote within that list. The district magnitudes in the majoritarian tier vary between one and six, dependent on, but not fully proportional to the population of each prefecture. In single-member constituencies, SNTV becomes equivalent to first-past-the-post, whereas seats are usually split between different parties/alliances in multi-member constituencies. Therefore, the single-member constituencies of the House of Councillors are more likely to swing the election result and often receive more media and campaign attention. The proportional election to the House of Councillors allows the voters to cast a preference vote for a single candidate on a party list. The preference votes strictly determined the ranking of candidates on party lists before 2019. Since the 2019 election, parties are allowed to prioritize individual candidates on their proportional list over voter preferences in a "special frame". In the 2019 election, almost all parties continued to use completely open lists; exceptions were the LDP which used the "special frame" to give secure list spots to two LDP prefectural federations affected by the introduction of combined constituencies in 2016, Reiwa Shinsengumi which used it to give secure list spots to two candidates with severe disabilities, and the minor "Labourers' Party for the liberation of labour".
File:Election in Japan2014.JPG|thumb|Voting in Higashiōsaka, Osaka Prefecture, Japan, 2014

Double elections

The electoral cycles of the two chambers of the Diet are usually not synchronized. When the 1947 constitution came into effect, the first House of Councillors election was held several days apart from the 23rd House of Representatives election. Only in 1980 and 1986, general and regular election coincided on the same day because the House of Representatives was dissolved in time for the election to be scheduled together with the House of Councillors election in early summer.

By- and repeat elections

Vacant district seats in both Houses are generally filled in by-elections. Nowadays, these are usually scheduled in April and October as necessary. Vacant proportional seats in both Houses and district seats in the House of Councillors that fall vacant within three months of a regular election are filled by : the highest ranking candidate on a proportional list or in the electoral district who was not elected and is not disqualified takes the seat. Disqualifications may, for example, happen if a candidate for the House of Councillors runs for the House of Representatives or vice versa, or after a violation of campaign laws.

Election of the Prime Minister

Between 1885 and 1947 in the Empire of Japan, the prime minister was not elected by the legislature, but responsible to, chosen and appointed by the Emperor. In practice, the usually nominated a candidate for appointment. The Imperial Diet and its elected lower house, the House of Representatives, which were set up in 1890 according to the Imperial Constitution, had no constitutionally guaranteed role in the formation of cabinets.
Since 1947, the Prime Minister has been chosen in the "designation election of the Prime Minister of Japan in the National Diet. It is held after a cabinet has submitted its resignation – the outgoing cabinet remains as caretaker cabinet until the Imperial inauguration ceremony of a new prime minister –; a cabinet must resign en masse under the constitution 1. always on convocation of the first Diet after a general election of the House of Representatives, 2. if the post of prime minister has fallen vacant – that includes cases when the prime minister is permanently incapacitated, e.g. by illness, kidnapping or defection –, or 3. if a no-confidence vote in the House of Representatives is not answered by the dissolution of the chamber. Though both Houses of the Diet vote in two-round elections to select a prime minister, the House of Representatives has the decisive vote: If the two Houses vote for different candidates, a procedure in the joint committee of both houses may reach a consensus; but eventually the candidate of the House of Representatives becomes that of the whole Diet and thereby prime minister-designate. The designated prime minister must still be ceremonially appointed by the Emperor in the Imperial Investiture to enter office; but unlike some heads of state, the Emperor has no reserve power to appoint anyone other than the person elected by the Diet.
In 2001, LDP president and Prime Minister Junichirō Koizumi instituted an advisory council to investigate the possibility of introducing direct popular election of the prime minister in a constitutional revision.