Japan’s 20 July 2025 upper house election saw the ‘Japanese First’ Sanseito surge from the fringe to mainstream, securing 14 seats in the 248-seat chamber, up from the one it had secured three years prior. Sanseito now holds enough seats independently to submit legislation in the Upper House, except for budget bills.
As nationalist rhetoric increasingly shapes the Japanese national debate, the question is whether Sanseito will follow the moderate course of some European populist parties or the confrontational path of the ‘America First’ movement and Europe’s far-right surge.
Party leader Sohei Kamiya told Reuters before the election that he drew inspiration from US President Donald Trump’s ‘bold political style’, particularly its confrontational stance, which he associated with the America First movement and the parallel rise of far-right parties in Europe. This self-identification highlights how Sanseito positions itself within a global repertoire of populist strategies.
But in the election, Sanseito recalibrated its strategy by foregrounding tax cuts and economic policies. This shift was an effort to reframe its populist appeal in more programmatic and material terms, broadening its support base beyond narrowly defined cultural or ideological grievances.
Japan has long prided itself on social harmony and relative political moderation, avoiding the deep partisan trenches of US politics. Yet this election exposed a truth that can no longer be ignored — Japan’s divisions are real, complex and growing, and Sanseito has skilfully turned these fractures into political capital.
Unlike the sharp Democrat–Republican split in the United States, Japan’s liberal–conservative divide is far narrower. While political parties are polarised on certain issues, many voters remain ideologically uncommitted. The clearest ideological fault line emerges in inter-party debates over security policy and constitutional reform, rather than over the size and role of government. This liberal–conservative divide also applies to only about half the electorate, beneath which lies a deeper divide between politically engaged citizens and those who have largely withdrawn from the political process.
Sanseito’s breakthrough came from winning over this latter group while eroding the governing Liberal Democratic Party’s conservative base, particularly among former Abe faction supporters. Its supporters were not traditional party loyalists. Many had long felt alienated from politics, convinced that established parties did not represent their struggles or concerns. This is what makes the party’s rise significant — it mobilised citizens whom conventional wisdom had written off as politically irrelevant.
At the heart of this surge was the so-called ‘employment ice age’ generation — numbering roughly 17 million nationwide — who came of age after the early 1990s economic collapse. Facing a brutal job market between the early 1990s and mid-2000s, many could not secure regular employment, instead working in temporary or part-time positions. Decades later, many remain economically insecure, with limited savings, unstable careers and growing anxiety about their future.
Now in their 40s and 50s, they turned out in force for Sanseito. Over 20 per cent of voters in this age bracket — the highest of any — backed the party in the proportional representation segment of the mixed-member system used to elect the upper house. For these voters, Sanseito’s message of national renewal, self-reliance and protection from perceived external threats had a powerful appeal.
Equally important was how Sanseito reached its audience. Bypassing traditional Japanese media, which are bound by neutrality rules under the Broadcast Act, Sanseito ran an aggressive digital campaign. Exit polls show that over 70 per cent of Sanseito’s supporters in the proportional race relied heavily on social media.
The party dominated online search trends, amassed over 100 million YouTube views and built tightly knit online communities on TikTok, YouTube and X (formerly Twitter). Supporters shared videos, memes and livestreams that reinforced their beliefs and fostered a sense of belonging while narrowing empathy for opposing views. This created an ‘us versus them’ dynamic reminiscent of echo chambers that have fuelled polarisation elsewhere, but without the large-scale partisan media infrastructure seen in the United States. These voters were more likely to distrust traditional media and institutions, making them more open to shifting political allegiances.
Immigration was Sanseito’s most potent rallying point. Japan’s foreign resident population stands at just 3 per cent of the total population, far below Germany’s 20 per cent or the United Kingdom’s 14 per cent. But in an aging society with chronic labour shortages, the party called for ending welfare benefits for foreigners, restricting their employment and enforcing stricter cultural conformity. This exclusionary rhetoric framing immigration as a threat to cultural and social cohesion struck a chord with voters whose anxieties are deeply tied to economic precarity and uncertainty about Japan’s future.
The message resonated not because immigration levels are high, but because it touched deeper anxieties about identity, fairness and economic security. For the ‘employment ice age’ generation in particular, whose economic prospects never recovered, these arguments offered a clear — if misleading — explanation for their struggles.
For now, Japan remains far from the extreme polarisation seen in the United States or parts of Europe. Successive governments have framed the acceptance of foreign workers as labour policy, not immigration policy, and debates over integration have been carefully avoided. The country’s political centre is still intact — but the ground beneath it is shifting.
Sanseito’s entry into the parliamentary mainstream will be the real test. Like Giorgia Meloni’s Brothers of Italy, some European populist parties have moderated once in power, recognising the constraints of governance. Others have hardened into exclusionary movements. The early months of the Trump administration serve as a cautionary tale of how quickly populist promises can morph into authoritarian politics.
Japan’s political future depends less on ideological battles between left and right than on preventing economic insecurity, social alienation and cultural anxiety from fuelling permanent political divisions. The upper house election showed that those on the political fringe can be mobilised, and their frustrations channelled, in ways that threaten the country’s tradition of social order and harmony.
With Japan’s severe aging and population decline, the country is more dependent than most on foreign workers. Immigration policy in its true sense is what should be debated in elections. The Japanese government must adopt a strategic immigration policy that addresses labour market needs and also aligns with the nation’s demographic goals in response to its declining population. To this end, it must implement measures to better integrate foreign residents into society, alleviating public anxieties, particularly those stemming from economic hardship and social instability.
Sanseito’s rise should be taken neither as a passing protest vote nor as an unstoppable wave. It is a signal — a warning — that the forces reshaping politics around the world are now firmly at Japan’s doorstep. The time to address the underlying cause is now, before the country’s quiet divisions grow into something far louder and far harder to repair.