Japan's Cabinet Secretariat has put numbers on who could qualify as a "sub-capital". Its draft cabinet order and ministerial ordinance set proposed thresholds under the new law on national social-function continuity and sub-capital development. Public comment runs from October 3 to October 16, 2026.
Where the law stands
The law (Law No. 78 of 2026, member-initiated legislation) passed the special Diet session, was promulgated on July 31 and takes effect on a date set by cabinet order within three months of promulgation. The comment window is shorter than the usual 30 days. The notice says the order must be set to match the law's entry into force. The schedule in the draft outline calls for the government ordinance to be promulgated at the end of October 2026.
The thresholds
The draft sets a hazard test for an alternative capital-function region, which the law defines as one with a low chance of being hit at the same time as the Tokyo area. A region would qualify only if it falls in neither the Tokyo inland-earthquake emergency countermeasure zone nor the Mount Fuji volcanic-disaster alert zone.
For sub-capital designation, the draft sets requirements under three headings of the law:
| Requirement | Draft threshold |
|---|---|
| Alternative capital-function region | Outside both the Tokyo inland-earthquake emergency countermeasure zone and the Mount Fuji volcanic-disaster alert zone |
| National administrative presence | Municipality with 14 or more regional branch bureaus of national government |
| Population | Designated city holding at least 1.2% of national population |
| Economy | Prefecture with output of at least 2.1% of national GDP |
| Local administration | Special wards under the large-city law, or a cooperation agreement under the Local Autonomy Act plus a promotion structure |
The draft outline does not name any city or prefecture that would meet the thresholds.
What a cooperation pact must contain
A prefecture and a designated city taking the pact route would have to draw up a joint basic plan for securing capital-function substitution and economic growth. They would also sign an agreement setting out which tasks they share, how roles are divided and how they cooperate, either by consultation or by joint handling of work. The draft lists eight areas of shared work, including industrial promotion, information and communications, education and research, urban planning, roads, rivers and ports, public facilities such as sports and conference venues, and disaster prevention. The last item is a catch-all for tasks that need to be handled jointly to keep administration unified.
The promotion structure carries its own duties. The two sides must jointly set up an internal body for the effort and hold a designated city-prefecture coordination meeting at least twice every fiscal year. Results of the talks must be reported to each assembly and published. Where a prefecture has several designated cities, it could sign similar pacts with those that do not meet all of the draft's requirements.
Comments go in through e-Gov or by post to the Cabinet Secretariat's sub-capital development office, in Japanese.