In Japan, Ruling Coalition’s Agreement on 10% Drop in Lower House Seats Sparks Pushback from Opposition

By Naohiro Tamura and Miyako Taniguchi / Yomiuri Shimbun Staff Writers

17:09 JST, October 24, 2025

Some opposition parties have expressed concern about reducing the number of seats in the House of Representatives, which the ruling coalition of the Liberal Democratic Party and the Japan Innovation Party have reached an agreement over.

Negotiations between the ruling and opposition parties are expected to face difficulties because, if the number of seats in the proportional representation segment of the house were to be reduced, it would deal a larger blow to small and midsize parties. Prospects are dim for the JIP’s request for a reduction at an early date.

The LDP and the JIP stated in their coalition agreement document that they would “reduce the number of House of Representatives members, with a target of a 10% reduction.” The coalition is aiming to pass legislation during the current extraordinary Diet session.

JIP Secretary General Hiroshi Nakatsuka appealed for cooperation when he met with his counterpart from the Democratic Party for the People, Kazuya Shimba, to discuss matters such as a reduction in seats, in the Diet Building on Thursday.

According to Shimba, Takashi Endo, chairman of the JIP Diet affairs committee and a special adviser to Prime Minister Sanae Takaichi, also attended the talks and said, “If it is not done in this Diet session, we will withdraw from the coalition at any time.”

Shimba told reporters that he was not opposed to a reduction in principle but asked that the ruling party’s proposal be presented first.

Of the 465 seats in the lower house, 289 are allocated to single-seat constituencies and 176 to the proportional representation segment. There is talk within both the LDP and JIP of reducing the number of proportional representation seats by 50 to achieve the 10% cut.

The 11 regional blocs that make up the proportional representation segment are assigned seats using the so-called Adams method, which emphasizes relative population.

According to an estimate by The Yomiuri Shimbun based on the results of the 2024 lower house election, if seats in the proportional representation segment were cut by 50, the number of seats in each regional bloc would decrease by between two and eight. By party, the LDP would see a decrease of 17 seats, followed by the Constitutional Democratic Party of Japan with nine, Komeito with six and the JIP with five.

By proportion of seats won in the election, including those in single-seat constituencies, the LDP would see a 9% decline, the CDPJ a 6% decline and the JIP a 13% decline. In contrast, Komeito and the Japanese Communist Party would see declines of 25%, and Sanseito and the Conservative Party of Japan would see declines of 67%, showing the increased impact on smaller parties.

Komeito is calling for the number of single-seat constituencies to also be reduced. At an intraparty meeting on Thursday, Komeito leader Tetsuo Saito criticized the LDP-JIP coalition, saying, “The ruling parties are trying to push ahead with a matter that concerns the very foundations of democracy.”

JCP leader Tomoko Tamura also objected to the move, saying, “This disregards public opinion,” while Sanseito leader Sohei Kamiya said, “This would crush emerging powers.”

Even within the LDP, there are voices saying that the issue should be discussed carefully while gaining the understanding of the opposition parties.

Koichi Hagiuda, the LDP’s executive acting secretary general, said in an online program broadcast on Thursday, “All parties and all diet groups must participate and find common ground.” He added that if the results of this year’s census are used as the basis for consideration, it will take time to achieve the reduction.

The JIP is keen to reach an early conclusion, but some LDP members are saying that submitting a related bill is probably the most that can be achieved in the current extraordinary Diet session.