Who is Sohei Kamiya, the populist firebrand shaking up Japanese politics?

The 47-year-old leader of the nationalist Sanseito party is gaining momentum ahead of Sunday’s Upper House elections

Sohei Kamiya, a little-known former Self-Defence Force reservist and political outsider, has emerged as a rising star in Japan’s political landscape. The 47-year-old leader of the nationalist Sanseito party is gaining momentum ahead of Sunday’s Upper House elections, drawing crowds of young voters with fiery speeches about “globalist threats,” immigration, taxes, and Japan’s national identity.

His party, Sanseito — which translates loosely to “participate in politics” — was founded just five years ago but is now polling third in a nationwide race, a remarkable feat in a country long dominated by the conservative Liberal Democratic Party (LDP). Kamiya himself is not on the ballot this year, having secured a six-year Upper House seat in 2022. But he has become the face of his fledgling movement, campaigning across Japan on behalf of 54 candidates — and hoping to turn his party into a durable political force, the New York Times reported.

A nationalist message with Trumpian overtones

Kamiya openly credits Donald Trump for shaping his approach, embracing the populist hallmarks of “Japanese First,” anti-globalism, and a rejection of traditional political elites. In campaign speeches, he rails against multinational corporations, foreign land ownership, rising immigration, and a political establishment he accuses of betraying Japan’s youth by prioritizing the interests of outsiders.

“Under globalism, multinational companies have changed Japan’s policies for their own purposes,” he declared at a rally in Kagoshima, standing atop a campaign truck near an active volcano. “If we fail to resist this foreign pressure, Japan will become a colony!”

While critics have labelled him xenophobic, Kamiya’s rhetoric has struck a chord with disillusioned younger voters, many of whom feel burdened by economic stagnation, high taxes, and what they see as government indifference to their generation. His calls to eliminate Japan’s 10 percent consumption tax — which funds services for the country’s aging population — and to reduce immigration have energized supporters.

From supermarket struggles to the national stage

Kamiya’s political worldview was shaped by early struggles. He worked in his father’s supermarket, which eventually went bankrupt, and studied in Canada before entering local politics. Disenchanted with the fundraising-driven culture of Japan’s ruling LDP, he left the party and founded Sanseito, which relies on small online donations rather than major donors.

The party’s outsider appeal and grassroots fundraising have helped it grow quickly. After winning a seat in the 2022 Upper House elections, Sanseito added another when a lawmaker defected from a rival party. Last year, it won three more seats in the Lower House. Now, with polls projecting it could capture 10 to 20 seats in the upcoming vote, Kamiya is positioning Sanseito as a serious challenge to the political mainstream.

A post-Abe vacuum — and an opening for populism

Analysts say Sanseito has capitalized on the vacuum left by former Prime Minister Shinzo Abe’s assassination in 2022. Abe, a powerful figure on the nationalist right, kept more extreme elements in check within the LDP. Without him, parties like Sanseito have attracted voters drawn to a more aggressive brand of identity politics.

“The LDP has been unable to hold onto the revisionist and xenophobic element that used to be contained in the Abe faction,” said Koichi Nakano, a Harvard-affiliated political scholar.

Prime Minister Shigeru Ishiba, facing falling approval ratings and pressure from emerging right-wing parties, has promised to address concerns about crime and foreign nationals. But his response — including a pledge to create a new government office for “harmonious coexistence” — has done little to stem support for Kamiya’s sharper message.

A movement or a moment?

While some political scientists view Sanseito as another short-lived protest party, Kamiya hopes Sunday’s results will prove otherwise. His ability to tap into generational frustration, bypass traditional media through YouTube and social media, and position himself as an alternative to status quo politics has made him one of Japan’s most closely watched political figures.

“I think Japan needs a political movement like ‘America First,’” Kamiya said in a recent interview. “But not the same leadership style — Trump is too self-centred for Japan.”

Whether Sanseito becomes a lasting force or a flash in the pan may hinge on how many seats it can secure this weekend — and how long Kamiya’s message resonates with a restless, younger electorate. For now, Sohei Kamiya is rewriting the playbook on Japanese populism.