Actor and anti-nuclear activist Taro Yamamoto and ex-wrestling star Antonio Inoki both won seats in Sunday's Upper House contest, early returns showed.

Yamamoto, 38, who ran as an independent in the Tokyo constituency, appeared set to enter the upper chamber after failing to win a seat in the Lower House election in December.

He became widely known for his anti-nuclear power activities following the March 2011 Fukushima meltdowns. He has also campaigned against Japan's participation in the Trans-Pacific Partnership trade liberalization negotiations, while calling for improved social security.

Inoki, 70, ran in the proportional representation segment for Nippon Ishin no Kai (Japan Restoration Party), which is jointly headed by former Tokyo Gov. Shintaro Ishihara and Osaka Mayor Toru Hashimoto.

The wrestling star won his first Upper House seat in 1989 as leader of the now-defunct Sports and Peace Party. In 1990, he helped negotiate the release of Japanese hostages in Iraq in the Persian Gulf War. He lost his seat in 1995.