Ishiba's ruling Liberal Democratic Party and its junior coalition partner Komeito were short three seats to maintain a majority in the 248-seat upper house in Sunday's vote.

The ruling coalition needs a total of 125 seats for a majority. They already have 75 uncontested seats, but NHK projections suggest it may be difficult for the Liberal Democratic Party (LDP) and Komeito to get the additional 50 needed.

Koeda Yoshiyuki, a 51-year-old supporter, called Sanseito “the only party that can truly tackle the big problems Japan faces today”. Sanseito relied on social media, especially YouTube, to reach voters disheartened with politics-as-usual.

This trend has in recent years fueled the rise of anti-immigrant far-right parties in Europe -- Alternative for Germany (AfD), France's National Rally (RN) and Austria's Freedom Party -- whose fortunes could offer clues to where Sanseito may be headed.

The success of new political parties focused on wages, immigration and an unresponsive political elite highlights the frustrations of many working-age people in Japan.

TOKYO >> Japanese Premier Shigeru Ishiba vowed to remain in his post on Monday after his ruling coalition suffered a bruising defeat in upper house elections, prompting some in his own party to doubt his leadership as the opposition weighed a no-confidence motion.

The success of Japanese right-wing party Sanseito in Sunday’s upper house election has the potential to unnerve global investors, who have been among the strongest supporters of the nation’s equity markets.

The opposition party Sanseito made a strong showing in the July 20 House of Councillors election in both constituency and proportional repres･･･