In single-seat districts across Japan’s countryside, local voters may quietly tip the electoral outcome and determine whether the ruling coalition can maintain its majority in the upper house.
The upper house election will take place on July 20. Japan’s 32 single-seat districts will play a decisive role in the fate of the ruling Liberal Democratic Party (LDP) and Komeito coalition.
The LDP-Komeito coalition lost its lower house majority in October 2024, and maintaining control of the upper house is essential for it to keep its policy agenda on track and avoid negotiating with opposition parties on every legislative item.
Many of Japan’s single-member districts, where only one seat is up for grabs, are traditionally strongholds of the LDP. However, early polling by Asahi Shimbun suggests the party is underperforming even in these areas.
The LDP-Komeito coalition already holds 75 uncontested seats from the previous election in 2022. This means it needs to win just 50 of the 124 contested seats to maintain a simple majority in the upper house. But even this relatively low benchmark is now seen as a challenge.
The upper house may not command as much attention as its lower counterpart. But it has the authority to stall or dismiss major legislation such as election promises based on economic stimulus, social security reform, energy, and national defense bills.
The upper house consists of 248 seats. But unlike a full lower house election, only half of the seats in the upper house come up for election every three years. This is due to Japan’s staggered system, where councilors serve six-year terms and elections alternate between the two halves of the chamber.
Japan’s staggered upper house elections began in 1947. The newly formed chamber needed a way to cycle half its members out every three years in order to ensure political stability, continuity and long-term oversight, unlike the lower house, which is subject to rapid political shifts.
Lawmakers turned to a randomized lottery. Half of the first group of councilors would serve a shortened three-year term, while the rest would stay on for the full six. The move laid the foundation for the existing cycle in which 124 seats were contested in 2022, with the remaining half set for election in 2025.
There is also one more additional seat in this year’s election. A by-election in Tokyo, triggered by the resignation of opposition Constitutional Democratic Party (CDP) lawmaker Saito Renho who left to pursue the Tokyo governorship, has raised the number of contested seats to 125.
Japan’s electoral map for the upper house is divided primarily by prefecture, with each district assigned a set number of seats based on population. Tokyo and Kanagawa, home to dense urban populations, elect four councilors each, while Hokkaido holds three.
Still, the system has struggled for decades to address disparities in regional-urban electoral representation. Until recently, even sparsely populated rural prefectures were guaranteed one seat, regardless of size. This design has increasingly clashed with Japan’s growing urban population and widened what is known as the “one vote disparity” problem, in which a ballot in a less populated area carries significantly more weight than one cast in a city.
In response, electoral reform was introduced ahead of the 2016 Upper House election. Typically, each electoral district equates to one of the country’s 47 prefectures. But to correct rapid depopulation in rural areas the government merged electoral districts in 2016. Under this system, some of Japan’s least populated prefectures were combined into a single electoral district. As a result, Tottori and Shimane prefectures now share one seat, as do Tokushima and Kochi prefectures.
Opposition parties, meanwhile, are aiming to flip enough contested seats to weaken the ruling bloc’s grip on power and reshape the direction of Japan’s policies. However, efforts by the main opposition parties to unite behind a single candidate have only succeeded in 15 of the single-seat districts. There is also growing momentum of parties like the center-populist Democratic Party for the People (DPFP) and the conservative, right-wing Sanseito could have a significant impact on the election outcome.
The opposition currently holds roughly 100 seats in the 248-member chamber. Opposition parties would need to win at least 25 more seats in this election to take control of the upper house. Even without securing a full majority, any gains that bring the ruling coalition below 125 seats would limit its ability to govern without negotiating with other blocs.
There is also a need to take swing voters into account. With a large portion of voters not tied to any party, late-breaking decisions and turnout fluctuations could upend forecasts in some of the tightest electoral battles.
The ruling coalition may no longer be able to count on its bank of uncontested seats. Its lackluster showing in the Tokyo assembly election in June 2025 has thrown the ruling coalition’s strategy into question. Forecasts suggest coordinated opposition efforts could yield as many as twenty seats in single-member districts. How unaffiliated voters respond at the polls may decide if the ruling bloc stays in power or falls short.
