Japan Innovation Party (Ishin) co-leader Fumitaka Fujita published his party's internal views on cutting the size of the House of Representatives on Oct 27, 2026, a day after the party's political reform committee met. The party should press ahead with the 45-seat reduction in the proportional representation tier that is already under continued deliberation, he wrote on X.
Fujita said a majority of members at the Oct 26 meeting wanted the party to push hard for the 45-seat cut. Ishin has not decided whether to support a rival plan to cut 31 seats, and will keep talking to other parties, he said.
The 31-seat figure is calculated from the fall in Japan's population between 2015 and 2030. Fujita argued that if the Diet accepts that logic, it should apply it every time the population falls.
A cut that keeps cutting
If population decline is the basis for the 31-seat plan, the same basis should hold for 2035 and 2040, Fujita wrote. Each national census — held every five years — should trigger a fresh reduction in proportion to the decline, and the bill should say so explicitly.
The 45-seat cut is the figure in the coalition agreement and in the party's election pledges, Fujita wrote, calling a 10% reduction a promise to voters. Ishin has long campaigned on shrinking the number of lawmakers, a cause that plays well with voters who see the Diet as bloated.
“If we adopt the logic of population decline, it is logically consistent and coherent to refer to the rate of decline at each future census, in 2035 and 2040, and cut the seats accordingly.”Fumitaka Fujita, Co-leader, Japan Innovation Party
Other proposals from the committee
Fujita's post also set out the party's positions on the other proposals from the committee chair. Members agreed strongly with raising the threshold for winning a proportional seat through the dual-candidacy route, from one-tenth to one-sixth of the valid vote.
Under Japan's parallel electoral system, candidates can run in both a single-seat district and on a party's proportional list. Those who lose their district can still enter the Diet if their share of the proportional vote clears the threshold.
The party also backed changing the formula for allocating proportional seats from the d'Hondt method to a modified Sainte-Laguë method, though with a caveat. Members noted that Japan has fewer parties than in 2012, when the old Democratic Party of Japan proposed a large seat cut — 15 parties contested the 2012 general election, against 12 before the 2025 vote.
- Leave a proportional seat vacant if a party's list is too short to fill it, and lower the threshold for forfeiting the deposit — supported
- Stop or reduce the party subsidy attached to a proportional lawmaker who leaves the party after the election — supported
- Make the cut in the proportional tier rather than in single-seat districts — strongly supported
On the subsidy, Fujita wrote that the current system, which lets a lawmaker keep their share of public funding after leaving the party, does not reflect the election result and is hard to justify to the public.
The debate over the size of the lower house has run for years without resolution. Any cut requires legislation, and the two tiers — single-seat districts and proportional blocs — have different defenders, which is why the parties keep circling the number.