Japan's main ruling Liberal Democratic Party has lost one of two Upper House by-elections. But it won the other and will retain that seat.

The by-elections took place in the Yamaguchi and Shizuoka constituencies on Sunday. They were held because two LDP lawmakers resigned.

With just a week to go before the Lower House election on October 31, the by-elections were widely seen as bellwethers.

In the Shizuoka constituency, an independent candidate, Yamazaki Shinnosuke, won with 650,789 votes. He defeated the LDP's Wakabayashi Yohei, who received 602,780 votes.

Yamazaki is a former member of a prefectural assembly. He was supported by the opposition Constitutional Democratic Party and the Democratic Party for the People.

In the Yamaguchi constituency, Kitamura Tsuneo won the by-election with 307,894 votes. Kitamura is a former LDP lawmaker. He was supported by the LDP's junior coalition partner Komeito. He defeated the opposition Japanese Communist Party's candidate, Kawai Kiyo, who received 92,532 votes.

The by-elections were the first national contests held since Prime Minister Kishida Fumio took office earlier this month.

The ruling and opposition camps sent party leaders and senior politicians out to campaign for the candidates.

The ruling parties say the setback in Shizuoka may have a limited impact on the upcoming Lower House election. But they say that more efforts need to be made in order to rally support for the ruling camp.

The opposition parties say the result indicates that voters are angry at the government. They also say that they hope it will give them momentum heading into the general election.