Japan's four opposition parties, ranging from advocates of small government to the Communists, said Wednesday they have selected their first common candidate to challenge the ruling party incumbent in the House of Councilors election next summer.

Running nominally as an independent, lawyer Hiromi Abe, 49, will pit herself against Yoshifumi Matsumura, 51, of the Liberal Democratic Party in the Kumamoto prefectural constituency, where one seat will be up for grabs in the triennial contest, they said.

She is the first candidate jointly chosen by the main opposition coalition — made up of the Democratic Party of Japan, the Japanese Communist Party, the Japan Innovation Party, which seeks a smaller government, and the Social Democratic Party — as they strategize to avoid cannibalizing each other's vote in the coming national poll.