The race is on to succeed Mr Fumio Kishida as leader of Japan’s ruling Liberal Democratic Party (LDP) and, hence, as the country’s prime minister, following his announcement on Aug 14 that he will not contest in scheduled party polls in September.
The key contest is for party president, with the vote likely to take place in the latter half of September.
Dr Sota Kato told The Straits Times that LDP politicians will be mindful that national elections for both chambers of the Diet are imminent when making their choice.

"Who might succeed Fumio Kishida as Japan’s prime minister?," The Straits Times
https://www.straitstimes.com/asia/east-asia/who-might-succeed-fumio-kishida-as-japan-s-prime-minister

Profile of Research Director Sota Kato
https://www.tkfd.or.jp/en/experts/detail.php?id=29