Tokushima-Kōchi at-large district

In the first election held for the combined district, the incumbent member for the Tokushima district, Yusuke Nakanishi, was selected as the ruling Liberal Democratic Party's candidate.[6] Hajime Hirota, the Democratic Party's incumbent member in the Kochi district, announced on 31 October 2015 that he would not contest the district as a protest against the merger.[7] In June 2016 it was reported that Hirota would instead contest one of Kochi Prefecture's districts at the next House of Representatives election, to be held by the end of 2018.[8] During the nomination period, the opposition Democratic, Communist, Social Democratic and People's Life parties formed an agreement to field a joint candidate in single-member districts such as Tokushima-Kochi.[9] Sō Ōnishi, a director of the Japan Federation of Bar Associations and president of the Tokushima Bar Association,[10] contested the election as an independent candidate with official endorsements from the Democratic, Communist and Social Democratic parties.[6] The third candidate was Masatoshi Fukuyama of the Happiness Realization Party.[6]

Nakanishi retained his seat in the Diet, receiving 54.1% of the vote compared to Ōnishi's 42.9%.[11] Nakanishi claimed 57.9% of votes cast within Tokushima, but the difference between the two main candidates within Kochi Prefecture was much closer, with Nakanishi and Ōnishi receiving 49.8% and 47.2% respectively.[12]

The overall voter turnout in the district was 46.26%,[4] the lowest in the nation, and both prefectures recorded their lowest turnout to a House of Councillors election.[13] By comparison, nationwide the turnout was 54.7%, a 2.1% increase from 2013.[14] Of the 592,092 voters to cast a vote in the district, 157,550 (26.6%) attended pre-polling booths in the two-week period before the July 10 election date.[15]

In Tokushima, the turnout was 46.98%, a 2.31% decrease from the previous election in July 2013. Amongst the eight cities of the prefecture, Tokushima city had the lowest turnout at 43.25%. Miyoshi recorded the highest turnout amongst the cities at 58.89%, but recorded a drop of more than 15% from its 2013 turnout. The city of Awa and town of Kamikatsu were the only municipalities within the entire electoral district to see an increase in turnout, with increases of 1.15% and 0.23% respectively.[16]

In Kōchi, which was not the home prefecture of any of the candidates, the turnout was 45.52%, a 4.37% fall from the previous election.[17] Turnout in Kōchi city and three other cities within the prefecture fell my more than 5%, and the village of Umaji saw a fall of almost 10%.[17] Attendance at pre-polling booths saw an increase from 20.3% of participating voters in 2013 to 25.9% in 2016.[17][18] On top of the poor turnout, 6.15% of those who turned out cast an invalid vote, compared to 3.55% in 2013,[19] and nine voters left the polling booth without submitting their ballot.[12]

Tokushima governor Kamon Iizumi said that the extremely poor turnout within the district was evidence of a problem and that the merger should be reversed, an issue that he would raise at the next meeting of the nation's governors.[13] Iizumi also called upon Nakanishi to become a flag bearer for regional revitalization, as it was the decline in population throughout rural Japan which led to the merger of the smaller districts.[13]

A revision to the electoral law came into effect three weeks before the election, which reduced the eligible age for voting from 20 to 18 years old.[20] The number of people enrolled to vote in Tokushima-Kōchi on the day of the election was 1,279,900, an increase of 18,800 (1.5%) compared to the annual survey conducted ten months earlier.[4][3]

Voters in the election also cast a second ballot in the 48-member national proportional representation block.[21] Voters have the option of voting for a specific candidate within a party, or for a party as a whole. Votes for specific candidates are used to determine who takes the seats won by the party. Tokushima's support for the conservative LDP and Komeito parties that make up the ruling coalition was 5.9% higher than the national average; conversely, Kochi's vote for the Communist Party was 6.7% higher than the national vote.