The current assembly is dominated by the ruling Liberal Democratic Party (LDP) and its long-time religious ally Komeito. Together, they have maintained a comfortable working majority which has supported, opposed and summarily dismissed the last two Tokyo governors — as well as pursuing notable pork barrelling.

But this unsavoury state of affairs seems about to end. Tokyo’s combative reformist Governor Yuriko Koike has constructed a ticket with major-party defectors and political novices. If it prevails on 2 July it will grant its leader the power to remake Tokyo’s finances, politics and even physical appearance, as well as possibly destabilise the balance of forces on the national level.

Koike won the governorship only ten months ago when the Tokyo branch of the LDP forced the mid-term resignation of Yoichi Masuzoe for misuse of political funds. Koike, an LDP member of the House of Representatives, immediately declared herself a candidate, becoming the first woman with a reasonable chance of leading Japan’s greatest metropolis. By not politely asking for the local LDP branch’s support for her candidacy beforehand, however, Koike angered local party grandees. When she could not proceed with the Tokyo LDP’s support, she forged ahead and won as an independent instead.

Once in power, Koike attacked many of her predecessor’s grand projects and political methods. She has postponed the move of the Tsukiji Fish Market after the new venue proved to be contaminated and improperly designed. She has skirmished with many Olympic groups over the size and costs of the 2020 Olympics. By halving her own salary as governor, she shamed Assembly members — who had enjoyed the highest salaries of any local legislators in the nation — into reducing their pay by 20 per cent.

Koike’s solid poll numbers (63 per cent in recent polls) and the powers of her office give her the ability to put many of her campaign promises into practice. She could function well as a maverick, running the city in a tug-of-war with the assembly.

But since last autumn, Koike has sought power beyond her office. In October she opened a ‘school’ (actually a series of lectures) for persons interested in becoming part of her core political cadres, from which she has developed the ‘raw material’ for a new party. In addition, Koike has been poaching candidates from the both the LDP and the DP.

Koike has also been forging improbable political alliances. In March, she received the formal allegiance of the Tokyo branch of Komeito, ending the long-standing Komeito–LDP alliance in Tokyo. In April, in a blow to the union-dependent Democratic Party, Koike exchanged a memorandum of understanding on policy matters with the Japanese Trade Union Confederation (RENGO). In halting the Tsukiji fish market move, Koike — despite being a member of the revisionist Nippon Kaigi and a frequent visitor to the infamous Yasukuni Shrine — has been working hand-in-glove with the anti-military, anti-revisionist Japan Communist Party.

Koike’s new party started operations on 1 June, one month before the assembly elections. But before leading her new party Tomin First no Kai (Tokyoites First), Koike had to erase an anomaly: she had to resign from the LDP. In a bizarre spectacle, Koike defeated an LDP-supported gubernatorial candidate, triggered defections from the LDP in the Tokyo assembly and formed a political party designed to seize the LDP’s majority in the assembly chamber, all while remaining a member in good standing of the LDP.

Despite seemingly having all her ducks lined up in a row, one question has loomed over Koike and her untested party: whether her personal popularity and frantic alliance building would translate into votes for her party in the assembly elections. To this, the answer seems to be a resounding yes. The 11–12 June Tokyo Shimbun poll found Koike’s party in first place with the support of 22 per cent of voters. In second place was the LDP, with 17 per cent support — nearly half the support the LDP enjoyed in the run-up to 2013 Assembly elections.

A Tomin First no Kai victory would see Japan’s top three core urban areas — Tokyo, Osaka and Nagoya — under the direction of regional, populist parties led by charismatic, media-savvy leaders. Two of these leaders share Abe’s enthusiasm for discarding ‘masochistic views’ of Japanese history and bolstering the military’s role. Komeito, which has served as a brake on revisionism for the past two decades, will be twisted into knots by its varying degrees of enmity and friendship with the national- and local-level LDPs. The DP, extirpated from Osaka by the rise of Restoration seven years ago, now faces annihilation and irrelevance in Tokyo as well.

The success of the established major parties in prefecture assemblies is under siege, and Koike’s likely success presages major shifts in prefecture–national government relations.

Michael Cucek is an Adjunct Professor of Political Science and History Temple University Japan and an Adjunct Professor of Social Science at Waseda University.