The election board of the Osaka municipal government decided Saturday to hold the mayoral election on March 23, after Mayor Toru Hashimoto tendered his resignation.
Hashimoto says he will seek re-election to achieve his controversial goal to merge the Osaka prefectural and municipal governments into a single metropolitan government by winning "a fresh mandate from voters."
Official campaigning will start on March 9.
Hashimoto, who is also co-head of the opposition Japan Restoration Party, on Friday informed the president of the municipal assembly of his intention to resign on Feb. 15. As the assembly is expected to vote to reject his resignation, however, Hashimoto will automatically lose the mayoral post on Feb. 27 under the local autonomy law.
Hashimoto could be re-elected without a vote, however, as the ruling Liberal Democratic Party, its coalition partner New Komeito party and the main opposition Democratic Party of Japan will forgo fielding a candidate, while the Japanese Communist Party has yet to decide whether to do so.