Exit polls suggest Prime Minister Shigeru Ishiba's coalition is likely to lose a majority its majority in the smaller of Japan’s two parliamentary houses in a key election.

Prime Minister Ishiba Shigeru and his Liberal Democratic Party were projected to lose their majority coalition government in Japan's Upper House of Parliament on Monday.

The ruling LDP and its junior partner Komeito both suffered significant losses amid widespread concerns over the rising cost of living and hostility to the political establishment as a whole.