2023 Ōita at-large district by-election

2023 Ōita at-large district by-election was held on 23 April 2023 because Kiyoshi Adachi resigned as a member of the House of Councillors.

Background
In 2019 election, Kiyoshi Adachi, a independent recommended by four opposition parties, including the Former CDP, defeated Yōsuke Isozaki, a current member of the House of Councillors belonging to the Liberal Democratic Party, and was elected for the first time in Ōita at-large district. Meanwhile, in the 2022 election, Shinya Adachi, a member of the opposition Democratic Party For the People and a current member of the Oita at-large district, lost to the ruling LDP candidate because of the division of the opposition camp.

Adachi announced his candidacy for Ōita Prefecture gubernatorial election and resigned as a member of the House of Councillors on March 10, 2023. With Adachi's resignation, by-elections will be held on April 28, 2023, under the Election Law.

The LDP has nominated Aki Shirasaka, the owner of Inaba, a club in Ginza, as its candidate. On the other hand, main opposition party, the CDP, nominated Tadatomo Yoshida, a former leader of the Social Democratic Party who left the SDP and joined the CDP in 2020, as a candidate.

After the assassination of Shuzo Abe, the LDP's collusion with the Unification Church was discovered, and the match drew national attention as it was a one-on-one battle between the ruling and opposition parties amid falling approval ratings of the Kishida administration.

Results
Shirasaka was elected for the first time by beating Yoshida by only 341 votes.