A plan to realign single-seat districts in the next Lower House election is expected to intensify an old rivalry between former Prime Minister Shinzo Abe and Foreign Minister Yoshimasa Hayashi — a political contest that could alter the balance of power within the ruling Liberal Democratic Party for years to come.

In 2016, after being pressed by the Supreme Court to address the issue of disparities in the size of the electorate in different constituencies, parliament adopted a proposal that would add seats to urban prefectures and take away seats in rural prefectures. The formula to be used for reducing the disparity, known as the Adams method, would be based on 2020 census data for each prefecture. Districts must be redrawn before the next Lower House election.

In 2021, census results showed that redistributing seats from 10 rural prefectures to five more urbanized ones would help reduce the disparity. Yamaguchi, Hiroshima, Okayama, Wakayama, Nagasaki, Ehime, Shiga, Niigata, Fukushima and Miyagi would lose one seat each. Tokyo would gain five seats, Kanagawa two seats, and Chiba, Saitama and Aichi would each gain one seat.