A government panel advised Prime Minister Fumio Kishida on Thursday that boundaries in a record 140 constituencies in 25 prefectures for House of Representatives elections should be revised to address vote weight disparities.
The changes would be the fourth since single-seat constituencies were introduced in 1994, affecting almost half of the country's 289 districts, and would reduce the vote weight disparity in Lower House elections from a potentially unconstitutional 2.096-fold difference to a 1.999-fold one.
Japan's top court has found disparities of more than 2.0 problematic, leading the government to work to resolve the potential issue.
The electoral council advised the removal of 10 constituencies and the addition of 10 elsewhere, with one removal each in Miyagi, Fukushima, Niigata, Shiga, Wakayama, Okayama, Hiroshima, Yamaguchi, Ehime and Nagasaki prefectures. The 10 new districts would be drawn in Tokyo and Kanagawa, Saitama, Chiba and Aichi prefectures.
The alterations would redistribute voting weight to urban areas from rural constituencies facing a rapid decline in population, which are traditionally ruling Liberal Democratic Party strongholds.
Yamaguchi Prefecture's reduction from four districts to three is especially noteworthy due to its concentration of LDP heavyweights.
Former Prime Minister Shinzo Abe, his younger brother Defense Minister Nobuo Kishi, Foreign Minister Yoshimasa Hayashi and Masahiro Komura, a parliamentary vice finance minister and son of former Foreign Minister Masahiko Komura, all hold seats there.
After receiving the advice, Kishida told reporters that the government "must take legal measures as quickly as possible."
He indicated that the government will submit a bill to amend the election law in an extraordinary parliamentary session possibly to be convened in the fall.