Thirty-One Seats, One Month: Japan’s Fight Over Cutting the Lower House Begins in Earnest
A bill that would shrink Japan’s House of Representatives is about to move from the clerk’s office onto the floor, and the argument around it is about to get louder. The ruling Liberal Democratic Party and its coalition partner, the Japan Innovation Party, also known as Nippon Ishin no Kai, want Lower House deliberations to start as early as Tuesday and want that chamber to pass the bill before the month is out.
Every opposition party except the Democratic Party for the People, which co-sponsored the text, is preparing to resist it. The three parties jointly submitted the legislation on Thursday. Their broader aim is to have it become law by 12 December, when the current Diet session is scheduled to end.
What the bill would actually change
The cut is precise, and that precision is the political problem. All 31 seats to be abolished would come from the proportional-representation tier. The 289 single-member districts would be left untouched. Japan’s lower chamber currently has 465 seats, 176 of them filled from party lists; if the bill passes, the house would shrink to 434.
The package does more than subtract chairs. It would merge the Chugoku and Shikoku proportional blocs, reducing the number of regional blocks from eleven to ten. Proportional seats would be handed out by a modified Sainte-Laguë method, which is meant to treat smaller parties more gently than the D’Hondt formula used now. At the same time, candidates who run both in a district and on a list, and who lose the district race, would need at least one-sixth of the valid votes in that district to be rescued by the list, up from the present one-tenth. If a party does not put up enough list candidates to fill the seats it has won, those seats would stay empty instead of being passed to someone else.
The sponsors say the smaller chamber simply reflects a country that is getting smaller. After an earlier plan to cut 45 proportional seats, roughly a tenth of the house, ran into resistance, the LDP proposed 31, pointing to a projected 6.7 percent decline in Japan’s population between 2015 and 2030. The three parties signed that compromise last month. Katsunobu Kato, the senior LDP lawmaker who heads the party’s task force on political reform, said he hoped they would now work together to get the bill through.
Why the opposition smells a trap
Komeito, the largest party in the Lower House’s main opposition bloc, argues that cutting only proportional seats would tilt the system further toward winner-take-all districts. The Japanese Communist Party says the package would make it harder for smaller parties to win seats and would weaken their voice. Even the shift to Sainte-Laguë, which on paper helps minor lists, may not offset the raw loss of 31 proportional chairs and the tougher threshold for defeated district candidates.
That is why the fight is expected to intensify this week. The arithmetic, however, is not on the resisters’ side. The LDP, the Japan Innovation Party and the Democratic Party for the People together hold majorities in both chambers of the Diet. If they stay united, they can pass the bill even without the rest of the opposition. Should it become law, the new rules would take effect together with a separate redrawing of single-member districts based on the 2025 census, possibly in 2027. The argument in the Diet is not only about how many lawmakers Japan should have. It is about which kind of lawmaker the next election is designed to produce.