Japan Approves Backup Capital Plan: What It Means if Tokyo Is Hit by a Major Earthquake

Japan’s parliament on Friday enacted legislation that clears the way for a secondary capital outside Tokyo to assume key national government functions if the capital is rendered inoperable by a major earthquake or other large-scale disaster.

The measure is designed to reduce Tokyo’s overwhelming concentration of political and administrative power while strengthening the country’s disaster preparedness.

After weeks of political deadlock, the House of Councilors voted to approve the bill on July 24, 2017, in a narrow 123-121 margin, which meant that lawmakers extended the parliament’s 150-day session by eight days, past its scheduled July 17 end.

The main opposition parties voted against the bill, and the ruling Liberal Democratic Party (LDP) and the Japan Innovation Party (JIP) were the strongest supporters.

Law Establishes Framework for a Backup Capital

The legislation gives the prime minister the authority to designate a backup capital among the prefectures that apply for and meet the government’s criteria such as population and economic capacity.

The designated city would take over the administration of the national government for a limited period of time in case the capital of Japan, Tokyo, loses its function during a major disaster.

The law does not name a specific city. Instead, it establishes the legal framework for selecting a secondary capital in the future.

Prime Minister Sanae Takaichi described the legislation as a landmark governance reform.

“This initiative is framed as a secondary capital plan that encompasses the Osaka merger plan. It’s a truly unprecedented reform of the nation’s governance structure. It’s immensely significant for enhancing national resilience and for establishing an economic hub outside the Tokyo metropolitan area,” Takaichi told reporters.

The initiative originated from a coalition agreement signed on Oct. 20, 2025, between the LDP and the JIP. The agreement secured the JIP’s support in parliament for Takaichi, who became Japan’s first female prime minister the following day.

Decentralization and Osaka’s Role

Although the legislation is nationwide in scope, it could provide fresh momentum for the JIP’s long-standing campaign to reorganize Osaka into a metropolitan government similar to Tokyo’s administrative structure.

JIP leader Hirofumi Yoshimura, who also serves as Osaka governor, has said he plans to hold a third referendum on the proposed Osaka metropolis alongside the next gubernatorial election in spring 2027. Similar referendums held in 2015 and 2020 were narrowly defeated.

To secure broader political support, lawmakers removed a provision that would have allowed a referendum on an Osaka city merger to be decided by voters across Osaka Prefecture. Legal scholars had argued the clause could conflict with Article 92 of Japan’s Constitution, which guarantees local autonomy.

Opposition Raised Concerns Over Political Motives

Opposition parties criticized the legislation, arguing it was structured primarily to benefit the Osaka-based JIP rather than advance nationwide decentralization.

Before allowing the bill to proceed to a vote, opposition lawmakers sought safeguards prohibiting local elections and constitutional referendums from being held on the same day, arguing simultaneous votes could influence referendum outcomes. The ruling coalition accepted revisions before the legislation was brought before the upper chamber.

In addition, during the parliamentary session, alterations were made to Japan’s constitutional referendum law, which would pave the way for a future national referendum on constitutional changes. The House of Councilors decided to use the English term “Senate” on its own.

Decades-Long Debate Over Tokyo’s Dominance

Tokyo has long been the hub of Japan’s political, bureaucratic and economic institutions, and many of the nation’s decision-making powers are aggregated in the Tokyo Metropolitan area.

The idea for distributing that concentration goes back to the early 1970s when former Prime Minister Kakuei Tanaka called for relocation of some government ministries. In 2000, there was a decentralization law to transfer some administrative responsibilities to local governments, which did not go far enough in redistributing the power from the national level.

The law passed Friday is the most important piece of legislation in Japan’s direction of establishing a formal system of backup governance and in moving power and authority away from the capital.