Official campaigning has kicked off for a second referendum in Osaka City on whether to reorganize the city into wards similar to those in Tokyo.

What is known as the "Osaka metropolis plan" calls for abolishing the city and creating four special wards. Those who proposed the plan say it will eliminate administrative redundancy between the city and Osaka Prefecture.

Official campaigning for a second referendum on whether to restructure Japan's western city of Osaka will begin on Monday.

The proposal involves reshaping the city into four wards, similar to Tokyo's 23-ward system. The city has more than 2.2 million eligible voters.

Official campaigning is to kick off in the race to choose the successor to outgoing Prime Minister Abe Shinzo as head of Japan's main governing Liberal Democratic Party.

Three lawmakers plan to file their candidacies on Tuesday. They are Chief Cabinet Secretary Suga Yoshihide; LDP policy chief and former foreign minister Kishida Fumio; and former LDP secretary-general Ishiba Shigeru.