Japan held elections for its upper house, the House of Councillors, on July 20. The vote proved a challenge for the conservative ruling Liberal Democratic party (LDP), which has been reeling from corruption scandals, rising prices and US tariffs on Japanese exports.

The ruling coalition, composed of the LDP and its junior partner, Kōmeitō, lost its majority in the house. While the centre-left Constitutional Democratic party maintained its position as the largest opposition group, the breakout success of the election was that of Sanseitō, an ultranationalist populist party.

Sanseitō successfully framed immigration as a central issue in the election campaign, with the provocative slogan “Japanese First”. The party won 14 seats in the 248-seat chamber, a substantial jump from the single seat it won in the last election in 2022.

Sanseitō calls itself a party of “ordinary Japanese citizens with the same mindset who came together”. It was formed in 2020 by Sōhei Kamiya, a conservative career politician who served as a city councillor in Suita, a city in Osaka Prefecture, before being elected to the House of Councillors.

Although Sanseitō was initially known for its stance against the COVID-19 vaccine, it has more recently campaigned on an anti-foreigner and anti-immigration platform. The party, which also holds three seats in the powerful lower house, has quickly gained seats in regional and national elections. It most recently won three seats in Tokyo’s prefectural elections in June 2025.

Sanseitō is “anti-globalist”, urging voters to feel proud of their ethnicity and culture. Polls suggest the party is popular among younger men aged between 18 and 30.

Throughout the most recent election campaign, Kamiya repeatedly spread far-right conspiracy theories and misinformation. This included arguing multinational corporations caused the pandemic, as well as that foreigners commit crimes en masse and can avoid paying inheritance tax. Social media has amplified Sanseitō’s xenophobic messaging.

Sanseitō’s electoral success is reminiscent of other right-wing populist parties across Europe and North America, which also place immigration as a core issue.

Kamiya denies being a xenophobe. But he has expressed support for the Republican party in the US, Reform in the UK, Alternativ für Deutschland in Germany and Rassemblement National in France. Echoing other right-wing populist leaders, Kamiya has promised tax cuts, home-grown industries, regulation of foreigners and patriotic education.

However, while Sanseitō rides the global wave of right-wing populism, it also has deeply Japanese roots. Following Japan’s defeat in the second world war, a distinct current of right-wing thought developed, defending “traditional values” and glorifying Japan’s imperial past.

Tensions have flared periodically over issues such as history education and official visits to Yasukuni Shrine, where those who died in service of Japan – including military leaders convicted of war crimes – are commemorated. There have also been disputes around the memorialisation of so-called “comfort women”, who were forced into sex slavery by Japanese forces before and during the war.

Building on these currents, Sanseitō represents a new generation of Japanese conservatism, not just an emulation of foreign populist leaders.

What happens next?

Sanseitō’s rise could have a pivotal influence on Japan’s political landscape. While the prime minister, Shigeru Ishiba, has indicated he will not resign, the ruling coalition has now lost control of both houses. Ishiba may need to seek support from other parties and may face leadership challenges.

He also must respond to issues Sanseitō has raised. LDP policymakers are now aware of public anxieties surrounding migration, excessive tourism and cultural integration. Seeking to co-opt some of Sanseitō’s proposals, the government has already banned tourists from driving and set up a new government agency to address concerns about non-Japanese nationals. It has also pledged to reduce illegal immigration to zero.

But the government is facing steep economic and demographic challenges, such as US tariffs, a rapidly ageing and declining population, and a record-low birth rate. So it cannot afford to cut immigration dramatically. Policymakers will have to balance economic needs with hardening public attitudes towards foreigners.

It’s not just immigration that will be at stake. Ishiba will need to navigate wedge issues that could split the LDP’s conservative support base. These include same-sex marriage, the use of separate surnames by married couples, and female succession to the throne.

It’s too early to say whether Sanseitō can sustain its momentum. Numerous populist leaders in Japan before Kamiya have succeeded in turning mistrust of the political class into votes at the ballot box. However, few have been able to translate it into meaningful political change across multiple election cycles.

For instance, Shinji Ishimaru made headlines in 2024 after placing second in the race for Tokyo governor. But his Path to Reform party, which promised educational reform, struggled in the latest election. Reiwa Shinsengumi, the left populist party led by Tarō Yamamoto, also enjoyed success in previous elections but remains small.

Only time will tell if Sanseitō will become a major political party or yet another minority group on the fringes. But it’s clear anti-immigration populism has arrived in Japan. And it looks like it’s here to stay.

Rin Ushiyama does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.