Elections in Japan

The Japanese political process has two types of elections.
 * National elections (国政選挙)
 * Subnational/local elections (地方選挙)

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 (統一地方選挙) 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 (公職選挙法) 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 (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 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 (about 27 thousand dollars) for a single-seat constituency and 6 million yen (about 54 thousand dollars) for proportional representation.

National elections
National elections include:
 * General elections of members of the House of Representatives (衆議院議員総選挙), 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 (参議院議員通常選挙), 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 (衆議院/参議院議員補欠選挙) to fill vacant majoritarian seats
 * Repeat elections of members of the House of Representatives/House of Councillors (衆議院/参議院議員再選挙) 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 (国会), has two directly elected chambers, elected on independent electoral cycles:

House of Representatives
The House of Representatives (衆議院) 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 (by the D'Hondt method) 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 (重複立候補) 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 ratio of margin of defeat (惜敗率) system determines the order of candidates.

House of Councillors
The House of Councillors (参議院) has 245 members (248 from 2022), elected for a fixed six-year term, 147 (2022–: 148) members by single non-transferable vote (SNTV) in 45 single- and multi-seat constituencies (most are prefectures, two combined constituencies comprise two neighbouring prefectures each) and 98 (2022–: 100) by proportional representation (by D'Hondt method) 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 (to determine proportional seat distribution), and as a preference vote within that list (to determine the order or proportional candidates 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 (and in the proportional constituency by definition). Therefore, the single-member constituencies of the House of Councillors (参議院一人区) 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" (特定枠). 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".

Double elections
The electoral cycles of the two chambers of the Diet are usually not synchronized. Even when the current constitution took effect in 1947, 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 roughly "being elected as runner-up" (繰り上げ当選): 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 Genrō (元老) usually nominated a candidate for appointment. The Imperial Diet (帝国議会) 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. https://www.ndl.go.jp/jikihitsu/e/part2/s2_1.html

Since 1947, the Prime Minister has been chosen in the "designation election of the prime minister" (内閣総理大臣指名選挙) (ja) 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 (Articles 69 and 70) 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 (as they did in 1948, 1989, 1998, 2007 and 2008), a procedure in the joint committee of both houses (両院協議会) 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 (親任式) 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.

April 2024 House of Representatives by-elections
On 28 April 2024, three by-elections were held: in Tokyo 15, Shimane 1 and Nagasaki 3. The CDP carried all three; amid extremely low approval ratings in the wake of the party kickback slush fund scandal, the LDP didn't contest Tokyo and Nagasaki (In Tokyo, Hirotada Ototake was supposed to be the LDP/Yuriko Koike affiliated candidate, but the LDP refused to endorse him), but also lost its previously unbroken "conservative kingdom" in Shimane.

October 2023 by-elections to both houses
In October 2023, two national by-elections were held on the same day as the prefectural assembly election in Miyagi. In Nagasaki's 4th House of Representatives district where Seigo Kitamura (LDP) had died in May, Yōzō Kaneko (LDP – Kōmeitō), the son of former Nagasaki governor and senator Genjirō Kaneko, held the seat for the ruling coalition by 7 points over centre-left opposition candidate Seiichi Suetsugu (CDP – SDP). The Tokushima-Kōchi senate seat had fallen vacant when Kōjirō Takano (LDP) had resigned after beating his secretary; the seat went to opposition-supported former Kōchi 2 House of Representatives member Hajime Hirota (I) who beat ruling coalition candidate Ken Nishiuchi (LDP – Kōmeitō) by more than 24 points.

April 2023 by-elections to both houses
Together with the second stage of the unified local elections, five national by-elections were held. The ruling coalition carried four, Nippon Ishin expanded beyond its Osaka base with an FPTP victory in Wakayama, the center-left opposition won none. The House of Councillors by-election in Ōita, the most clear-cut one-on-one government/opposition contest of the evening, was decided in favour of government candidate Aki Shirasaka (LDP – Kōmeitō) by less than 400 votes over Tadatomo Yoshida (CDP – JCP, SDP).

2022 House of Councillors regular election
Results summary:
 * Proportional tier (1 nationwide constituency, 50 seats), turnout 52.04%
 * LDP 33 candidates, 34.4% of votes, 18 seats (36% of seats)
 * Ishin 26 candidates, 14.8%, 8 seats (16%)
 * CDP 20 candidates, 12.8%, 7 seats (14%)
 * Komeito 17 candidates, 11.7%, 6 seats (12%)
 * JCP 25 candidates, 6.8%, 3 seats (6%)
 * DPFP 9 candidates, 6.0%, 3 seats (6%)
 * Reiwa Shinsengumi 9 candidates, 4.4%, 2 seats (4%)
 * Sanseitō 5 candidates, 3.3%, 1 seat (2%) and legal status as national-level political party
 * SDP 8 candidates, 2.4%, 1 seat (2%) and defended legal party status
 * NHK Party 9 candidates, 2.4%, 1 seat (2%) and defended legal party status
 * 5 other parties (aggregate) 17 candidates, 1.1%, no seats
 * Majoritarian tier (45 constituencies, 74 seats+1 integrated by-election to the other class), turnout 52.05%
 * Governing parties (LDP+Komeito): 56 candidates, 45.5% of votes, 52 seats (69.3% of seats)
 * CDP 31 candidates, 15.3%, 10 seats (13.3%)
 * Ishin 20 candidates, 10.4%, 4 seats (5.3%)
 * DPFP (cooperating with the CDP in some districts, competing in others) 13 candidates, 3.8%, 2 seats (2.6%)
 * JCP (cooperating with the CDP in few districts, competing in most) 33 candidates, 6.8%, 1 seat (1.3%)
 * Reiwa Shinsengumi 5 candidates, 1.9%, 1 seat (1.3%)
 * Independents: 35 candidates (some of them party-endorsed) 8.1%, 5 seats (6.7%, four of them opposition-endorsed)
 * Others (aggregate) 174 candidates, 8.2%, no seats

2022 House of Councillors by-election
The April 24 by-election in Ishikawa to the 2019–25 class of the House of Councillors was safely won by government candidate Shūji Miyamoto (LDP-Komeito, 68.4%) against Tsuneko Oyamada (CDP-SDP, 21.6%) and candidates from JCP and NHK party. The seat had been vacated in December 2021 by Shūji Yamada (LDP) for his (unsuccessful) candidacy in the gubernatorial election in March.

2021 House of Representatives general election
The LDP defended its majority, and the LDP-Kōmeitō coalition government continues under prime minister Fumio Kishida; but the coalition no longer holds a two-thirds majority as it had previously since 2012, i.e. it now needs to retain its majority in the House of Councillors in order to control a legislative majority of its own in parliament. The main opposition CDP picked up some majoritarian seats in a joint centre-left nomination strategy, but lost substantially in the proportional tier where it had held almost the same number of seats as the LDP before the election due to the 2020 party realignments. The centre-right opposition Ishin no Kai surged, winning 15 of 19 FPTP seats in Osaka and gaining seats in ten of eleven proportional districts countrywide.


 * Proportional tier (11 constituencies, 176 seats), turnout 55.92%
 * LDP 59 PR-only + 251 dual candidates, 34.7% of votes, 72 seats (41% of seats)
 * CDP 26+213 candidates, 20.0%, 39 seats (22%)
 * Ishin 2+94 candidates, 14.0%, 25 seats (14%)
 * Komeito 44+0 candidates, 12.4%, 23 seats (13%)
 * JCP 25+15 candidates, 7.2%, 9 seats (5%)
 * DPFP 6+21 candidates, 4.5%, 5 seats (3%)
 * Reiwa Shinsengumi 9+12 candidates, 3.9%, 3 seats (2%)
 * 6 other parties (aggregate) 40 candidates, 3.4%, no seats
 * Majoritarian tier (289 constituencies, 289 seats), turnout 55.93%
 * Governing parties (LDP+Komeito): 286 candidates (cross-endorsed practically countrywide), 49.6% of votes, 196 seats (67.8% of seats)
 * Centre-left opposition (CDP+DPFP+JCP+SDP+ReiShin): 361 candidates (joint in about two-thirds of constituencies, competing against each other in the rest), 37.7%, 65 seats (22.5%)
 * Ishin: 94 candidates, 8.4%, 16 seats (5.5%)
 * Independents: 80 candidates (including several endorsed by the LDP) 3.9%, 12 seats (4.2%, including two winners retroactively nominated by the LDP)
 * Others (aggregate) 36 candidates, 0.4%, no seats

Malapportionment
In the 1980s, apportionment of electoral districts still reflected the distribution of the population in the years following World War II, when only one-third of the people lived in urban areas and two thirds lived in rural areas. In the next forty-five years, the population became more than three-quarters urban, as people deserted rural communities to seek economic opportunities in Tokyo and other large cities. The lack of reapportionment led to a serious underrepresentation of urban voters. Urban districts in the House of Representatives were increased by five in 1964, bringing nineteen new representatives to the lower house; in 1975 six more urban districts were established, with a total of twenty new representatives allocated to them and to other urban districts. Yet great inequities remained between urban and rural voters.

In the early 1980s, as many as five times the votes were needed to elect a representative from an urban district compared with those needed for a rural district. Similar disparities existed in the prefectural constituencies of the House of Councillors. The Supreme Court had ruled on several occasions that the imbalance violated the constitutional principle of one person-one vote. The Supreme Court mandated the addition of eight representatives to urban districts and the removal of seven from rural districts in 1986. Several lower house districts' boundaries were redrawn. Yet the disparity was still as much as three urban votes to one rural vote.

After the 1986 change, the average number of persons per lower house representative was 236,424. However, the figure varied from 427,761 persons per representative in the fourth district of Kanagawa Prefecture, which contains the large city of Yokohama, to 142,932 persons in the third district of largely rural and mountainous Nagano Prefecture.

The 1993 reform government under Hosokawa Morihiro introduce a new electoral system whereby 200 members (reduced to 180 beginning with the 2000 election) are elected by proportional representation in multi-member districts or "blocs" while 300 are elected from single-candidate districts.

Still, according to the 6 October 2006 issue of the Japanese newspaper Daily Yomiuri, "the Supreme Court followed legal precedent in ruling Wednesday that the House of Councillors election in 2004 was held in a constitutionally sound way despite a 5.13-fold disparity in the weight of votes between the nation's most densely and most sparsely populated electoral districts".

The 2009 general House of Representatives election was the first unconstitutional lower house election under the current electoral system introduced in 1994 (parallel voting and "small" FPTP single-member electoral districts/"Kakumander"). In March 2011, the Grand Bench (daihōtei) of the Supreme Court ruled that the maximum discrepancy of 2.30 in voting weight between the Kōchi 3 and Chiba 4 constituencies in the 2009 election was in violation of the constitutionally guaranteed equality of all voters. As in previous such rulings on unconstitutional elections (1972, 1980, 1983 and 1990 Representatives elections, 1992 Councillors election), the election is not invalidated, but the imbalance has to be corrected by the Diet through redistricting and/or reapportionment of seats between prefectures.

In 2016, a panel of experts proposed to introduce the [John Quincy] Adams apportionment method (method of smallest divisors) for apportioning House of Representatives seats to prefectures. The reform is planned to be implemented after the 2020 census figures are available and not expected to take effect before 2022. In the meantime, another redistricting and apportionment passed in 2017 is designed to keep the maximum malapportionment ratio in the House of Representatives below 2. In the FPTP tier, it changes 97 districts and cuts six without adding any; in the proportional tier, four "blocks" lose a seat each; the total number of seats in the lower house is cut to 465, 289 majoritarian seats and 176 proportional seats.

The malapportionment in the 2010 and 2013 regular House of Councillors elections was ruled unconstitutional (or "in an unconstitutional state") by the Supreme Court, and has been reduced by a 2015 reapportionment below 3 (at least in government statistics from census data which is regular and standardized but lags behind resident registration statistics and the actual number of eligible voters; using the latter, the maximum malapportionment in the 2016 election remained slightly above 3 ).

The following table lists the 10 electoral districts with the highest and lowest number of registered voters per member elected for each chamber of the National Diet according to the voter statistics as of September 2016 released by the Ministry of Internal Affairs and Communications – it takes into account the lowering of the voting age and the district reforms to both houses of the Diet in effect since the 2014 and 2016 elections, but not the 2017 redistricting/reapportionment effective from the next House of Representatives election.

Prefectural and local elections
Local elections include:
 * Prefectural elections
 * Prefectural gubernatorial elections (都道府県知事選挙) on an independent four-year cycle
 * General/by-/repeat elections of members of a prefectural assembly (都道府県議会議員一般/補欠/再選挙), general elections are held on an independent four-year cycle
 * Municipal elections
 * Municipal mayoral elections (市区町村長選挙) on an independent four-year cycle
 * General/by-/repeat elections of members of a municipal assembly (市区町村議会議員一般/補欠/再選挙), general elections are held on an independent four-year cycle

There are 47 prefectures (-to/-dō/-fu/-ken) of Japan since 1888, they are contiguously subdivided into 1741 municipalities (-shi/-ku/-chō/-son) since 2014 (see Administrative divisions of Japan).

Unified elections
Unified local elections (統一地方選挙 tōitsu chihō senkyo) are held once every four years. Prefectural assemblies and governors, as well as mayors and assemblies in municipalities, are elected for four-year terms. In April 1947, all local elections in the 46 prefectures (excluding Okinawa Prefecture, then under US military rule) and all their municipalities were held at the same time in "unified local elections". Since then, some gubernatorial and mayoral elections, and most assembly elections, have stayed on this original four-year cycle. Most governors and mayors are now elected on different schedules as the four-year cycle "resets" upon the resignation, death or removal of a sitting governor or mayor. Some assembly election cycles have also shifted due to assembly dissolutions or mergers of municipalities.

The most recent were the 2023 Japanese unified local elections.

As of 2015, the major contests in the unified local elections are as follows:

Although Tokyo's metropolitan governor and assembly elections are currently held on separate schedules, 21 of the 23 special wards of Tokyo follow the unified election schedule for their assembly elections, the only exceptions being Katsushika and Adachi. The majority of Tokyo's special wards follow separate cycles for their mayoral elections. Tokyo elected its governor as part of the unified elections until 2011, but was forced to hold a 2012 election and 2014 election due to the resignations of Shintaro Ishihara and Naoki Inose.

Iwate Prefecture, Miyagi Prefecture and Fukushima Prefecture are no longer on the unified election cycle due to the 2011 Tohoku earthquake and tsunami, which delayed their elections.


 * List of unified local elections
 * 2007 Japanese unified local elections
 * 2011 Japanese unified local elections
 * 2015 Japanese unified local elections
 * 2019 Japanese unified local elections

Other major local election cycles

 * Since 1971, Ibaraki Prefecture has held its prefectural assembly elections in the December preceding the unified election, making this election a regular leading indicator of the nationwide elections in the following April. The 2014 Ibaraki election was held on the same day as the 2014 Japanese general election.
 * Approximately 193 new municipalities were created in a wave of "Heisei mergers" effective in April 2005. Their first municipal elections were held around this time, and coincided with the Chiba and Akita gubernatorial elections and the Nagoya mayoral election, creating a second major local election cycle sometimes referred to as the "mini unified local elections."
 * Okinawa Prefecture and most of its local governments continue to follow a four-year cycle that began following repatriation to Japan in June 1972, with several exceptions (including the city of Naha). Okinawa elections generally occur in the year following the unified elections; the next is scheduled for June 2016.

Ballots, voting machines and early voting


Votes in national and most local elections are cast by writing the candidate's or party's name on a blank ballot paper. In elections for the House of Representatives voters fill in two ballots, one with the name of their preferred district candidate and one with their preferred party in the proportional representation block. For the House of Councillors, the district vote is similar (in SNTV multi-member districts, several candidates can be elected, but every voter has only one vote). But in the proportional vote for the House of Councillors votes are cast for a party list (to determine how many proportional seats a party receives) or a candidate (which additionally influences which candidates are elected from a party's list).

Ballots that cannot unambiguously be assigned to a candidate are not considered invalid, but are assigned to all potentially intended candidates proportionally to the unambiguous votes each candidate has received. These so-called "proportional fractional votes" (按分票) are rounded to the third decimal. For example, if "Yamada A" and "Yamada B" both stood in an election and there were 1500 unambiguous votes: 1000 for "Yamada A" and 500 for "Yamada B"; five ambiguous votes for "Yamada" would then count for Yamada A as 5×1000/1500=3.333 votes, and for Yamada B as 5×500/1500=1.667 votes. The official overall result would then be: Yamada A 1003.333 votes, Yamada B 501.667 votes.

In 2002, passage of an electronic voting law allowed for the introduction of electronic voting machines in local elections. The first machine vote took place in Niimi, Okayama in June 2002. In 2003, a system for early voting (期日前投票制度) was introduced. In the 2017 general/House of Representatives election, a record number of more than 21 million Japanese voted early; at the same time overall turnout was low (the second lowest in history), so in 2017, roughly 38% of all actual voters had voted early. For regular/House of Councillors elections, the 2019 election set a new all-time high with more than 17 million early voters, corresponding to roughly a third of actual voters in 2019 as overall turnout hit the second lowest value in history.

Walkovers
In Japan, walkovers in elections are called Mutōhyō tōsen (無投票当選), "[being] elected without vote". And there is literally no vote held in a walkover in Japan, no way to vote "no" or abstain explicitly: If there are only as many candidates in an election as there are seats/offices at the start of the legal election period ("official announcement": kōji (公示) in national general and regular elections; kokuji (告示) in prefectural and municipal elections as well as national by-elections), they are declared the winners. But the otherwise applicable moratorium period after regular elections on recall attempts does not apply after a walkover. (Recalls are a two-/three-step procedure: first, supporters of a recall must collect a sufficient number of signatures; if they do, a referendum is held on whether or not to recall the incumbent; only if that is accepted by a majority, a fresh election is scheduled.) Article 100 of the Public Offices Election Law deals with walkovers, there are additional walkover provisions for subnational elections in the Local Autonomy Law.

Walkovers have become widespread in prefectural and municipal elections in recent years; in the 2019 unified local elections, out of 2277 seats up in 945 electoral districts for 41 prefectural assemblies, a record 612 seats are won by walkovers in a total of 371 districts or 39% of all electoral districts. In one extreme case, a rural single-member electoral district to the Shimane prefectural assembly, there hasn't been a contested election in 31 years (the whole Heisei period).