Japan's prime minister said Monday that he accepts his ruling Liberal Democratic Party's unexpected defeat in one of two parliamentary by-elections held just a week out from the country's general election.

The LDP, led by Prime Minister Fumio Kishida, lost in Shizuoka prefecture, southwest of Tokyo, in one of the races for vacant seats held on Sunday.

Shinnosuke Yamazaki, an independent candidate backed by the main opposition Constitutional Democratic Party of Japan (CDPJ) emerged victorious in a close race with the LDP candidate, Yohei Wakabayashi.

However, the ruling party won the upper chamber seat in another prefecture, Yamaguchi.

"We won people's confidence in Yamaguchi, but saw a disappointing result in Shizuoka. I would like to solemnly accept the judgment of people in (Shizuoka)," Kishida told reporters on Monday.