The Liberal Democratic Party, Nippon Ishin no Kai and the Democratic Party for the People agreed on draft bill language on the 9th to cut 31 proportional representation seats and merge the Chugoku and Shikoku blocks, reducing the Lower House from 11 proportional blocks to 10.
The three parties aim to formalize the agreement as early as the 12th, after internal party procedures, and to submit the bill jointly to the Lower House within the week. The change would cut the Lower House's total membership from 465 to 434.
The bill would take effect on the same day as a redistricting bill expected to be submitted to the Diet and enacted in 2027, which is meant to correct the disparity in the weight of votes between single-seat districts.
A stopgap until a panel reports
The reforms are positioned as a stopgap until a new expert panel under the Speaker of the Lower House reaches conclusions on a fundamental overhaul. The cut from 176 to 145 proportional seats is based on a projected population decline of 6.7% over 15 to 30 years.
The merged Chugoku-Shikoku block would hold 13 seats, three fewer than the two blocks hold now, with Chugoku at 10 and Shikoku at 6.
- Kinki: down 5
- Minami-Kanto and Tokai: down 4 each
- Kita-Kanto, Tokyo and Kyushu: down 3 each
- Hokkaido, Tohoku and Hokuriku-Shinetsu: down 2 each
Seats would be allocated under a modified Sainte-Laguë method designed to take smaller parties into account.