On the day of a snap winter election – one that would ultimately end in a landslide victory for the Liberal Democratic Party (LDP) – Takaichi  Sanae stood alongside two men. They were not members of her own party, but rather the two leaders of Nippon Ishin no Kai: Osaka Governor Yoshimura Hirofumi and Fujita Fumitake, who leads his party’s Diet delegation. Yet Yoshimura’s stump speech hardly sounded like one delivered by the leader of a different party. In fact, it barely sounded as though Takaichi herself belonged to the LDP.

“We may not have the numbers. But we will never back down. We will not leave Takaichi-san standing alone,” Yoshimura declared. “We will not let Japan stand alone. We are determined to move Japan forward. That is the resolve with which we stand here today.”

Before they joined the ruling coalition, Nippon Ishin’s initial favorite in the October 2025 LDP leadership race was Koizumi Shinjiro, now serving as minister of defense. They shared a commitment to challenging vested interests and embraced what are often described as “neoliberal” approaches to achieving that goal. By providing the LDP with enough votes to secure a parliamentary majority – which it lacked in both houses at the time – Nippon Ishin hoped to advance a reform agenda that would have been impossible to pursue as a mid-sized opposition party alone. 

Although Yoshimura never explicitly endorsed a preferred successor to Ishiba Shigeru, his description of Koizumi as a “politician who embodies the spirit of reform” and “a true reformer” left little doubt about his own – and his party’s – preferred candidate. Consequently, Takaichi’s victory came as a shock to Nippon Ishin. The party had not only expected Koizumi to prevail but also lacked close political ties to Takaichi and her inner circle.

However, the events that unfolded after Takaichi’s election opened a window that had long been thought closed. The LDP’s longtime coalition partner, Komeito, declined to form a government under her leadership, citing frustration with the LDP’s handling of the political funding scandal and doubts that the reforms Komeito sought would be implemented on its preferred timetable. As a result, the once-automatic path from LDP president to Japanese prime minister was no longer assured. The former members of the Democratic Party of Japan were seeking to reassemble. During the ensuing political deadlock, Takaichi wryly referred to herself as “the woman who may never become prime minister.”

Then came Nippon Ishin to the rescue. With the help of  Takashi Endo of Nippon Ishin – who is well known for his cross-party connections and served as an intermediary between Yoshimura and Takaichi – Yoshimura came to see Takaichi as a fellow reformer, while Takaichi, in turn, came to believe that they had more in common than she had initially thought. The coalition talks gained speed, and a week after the leaders talked, there was a coalition agreement. 

Since becoming prime minister, Takaichi has begun implementing key elements of the coalition agreement, many of which had already been on her own policy agenda for years and were included in her campaign platform during the February election. One example is the bill criminalizing the desecration of the Japanese flag – a measure she unsuccessfully sought to enact in both 2012 and 2021. 

Likewise, the security reforms now underway reflect a longstanding agenda of LDP conservatives, including Takaichi, who had long argued that Komeito constrained their ambitions. With Nippon Ishin replacing Komeito as the LDP’s coalition partner, those constraints have largely disappeared. Although the coalition agreement was not exclusively focused on security, it was disproportionately heavy on that area, enabling the LDP’s conservative wing to pursue long-sought defense and public security reforms. 

At the same time, Takaichi’s political indebtedness to Nippon Ishin is widely cited as a reason her government has embraced policies that were not previously among her priorities. The extent of that indebtedness was evident when she introduced legislation to reduce the number of seats in the House of Representatives by 10 percent, explaining that the proposal was a promise the LDP made to Nippon Ishin. The measure provoked fierce opposition, particularly from parties that rely heavily on proportional representation, where most of the proposed seat reductions would have occurred, prompting them to boycott Diet deliberations. 

Although Takaichi ultimately withdrew the bill after consulting Yoshimura, her willingness to press ahead with such a politically contentious proposal underscored the extent to which she felt compelled to accommodate her new coalition partner. Despite Nippon Ishin lacking the electoral machine that Komeito had, Takaichi seems not to have forgotten the helping hand her new partner extended to her.

Some observers have described Nippon Ishin as “Takaichi’s faction,” suggesting that it has effectively become her political power base outside the LDP. The characterization aptly captures Takaichi’s position within her own party. Long regarded as an outsider within the LDP, she reached the pinnacle of power not by cultivating the support of party elders, but by building a strong following among the conservative grassroots and forging a close political alliance with late Prime Minister Abe Shinzo, the party’s leading conservative figure. Her decision to call a snap election in early 2026 was partly motivated by a desire to consolidate her grip on a party that still included many moderates and fiscal conservatives who remained skeptical of her social conservatism and support for expansionary fiscal policy.

At least, that was how Nippon Ishin appeared to interpret it. While campaigning during the snap election, Nippon Ishin Secretary General Hiroshi Nakatsukasa argued that “there are still forces of resistance within the LDP,” adding, “Our job is to keep a close watch on that. We will support the prime minister, keep politics moving forward, and serve as the accelerator for the government.” The remarks underscored the party’s self-perception as both Takaichi’s protector against resistance within the LDP (“We will not leave Takaichi-san standing alone”) and the driving force behind her reform agenda (“We are determined to move Japan forward”).

There are growing calls within the LDP to reconsider the coalition with Nippon Ishin now that the party enjoys a supermajority on its own, with some arguing that Nippon Ishin’s neoliberal agenda has become more of a nuisance than an asset. Yet for a party founded on the principle of decentralizing Japan’s governing apparatus, the passage of the deputy capital bill represents a significant achievement, and the fact that the LDP extended the Diet session just for that purpose attests to Takaichi’s resolve to pay back her debt. 

Takaichi and the LDP’s defense hawks may increasingly come to view Nippon Ishin as an external catalyst capable of nudging the party further to the right on constitutional revision and a more forward-leaning nuclear policy, including support for nuclear-sharing arrangements with the United States.

The differences between the two parties are perhaps most evident in the Diet’s Commission on the Constitution, the parliamentary committee responsible for deliberating constitutional amendments. While the LDP seeks to preserve the existing wording of Article 9, Paragraph 2 – which renounces the maintenance of “war potential” – Nippon Ishin advocates deleting Paragraph 2 altogether and replacing the Self-Defense Forces with a constitutionally recognized National Defense Force. 

More broadly, the debate over Japan’s defense posture highlights the divide between Takaichi and her intra-party rivals. Whereas her opponents have generally preferred a more incremental approach to constitutional reform and defense policy, Takaichi’s strengthened position – further reinforced by cooperation with Nippon Ishin – has left them with little room to publicly challenge her agenda.

Although Nippon Ishin may increasingly find itself marginalized by the LDP’s overwhelming parliamentary majority, and several of its signature policy goals – including a ban on corporate and organizational political donations and sweeping social security reform – remain in limbo, many of its priorities, particularly in the areas of national security, are being incorporated into government policy. Once widely viewed as a party in decline, Nippon Ishin has, through its alliance with Takaichi, exerted an influence on the Japanese government that far exceeds its parliamentary strength.