The nationwide district elected 50 members by D'Hondt proportional representation with optionally open lists, the previous most open list system was modified in 2018 to give parties the option to prioritize certain candidates over the voters' preferences in the proportional election.

[1][2] The election saw Prime Minister Shinzo Abe's ruling coalition lose the two-thirds majority needed to enact constitutional reform.

[6] The governing coalition would have to lose 30 seats or more to forfeit its overall majority in the House of Councillors and face a technically divided Diet.

However, as independents and minor opposition groups might be willing to support the government on a regular basis without inclusion in the cabinet, the losses required to face an actual divided Diet may have been much higher.

If the Diet is divided after the election, the coalition's two-thirds majority in the House of Representatives can still override the House of Councillors and pass legislation, but certain Diet decisions, notably the approval of certain nominations by the cabinet such as public safety commission members or Bank of Japan governor, would require the cooperation of at least part of the opposition or an expansion of the ruling coalition.