TOKYO -- Voting for Japan's upper house election began on Sunday morning, with a total of 522 people running in the intensive battle between the ruling and opposition camps.

The House of Councillors is made up of 248 members with six-year terms. Elections are held every three years, with half the seats up for grabs each time. Voters are weighing in on a total of 125 seats in Sunday's poll, including one where a contest is needed to fill a vacancy.

Currently, the ruling Liberal Democratic Party and its junior ruling partner Komeito have 75 seats that are not up for re-election. Therefore, the embattled coalition, which faces bad media poll numbers, must secure 50 seats in this election to maintain a majority in the 248-seat chamber.

The bar is seen as relatively low for the ruling bloc, which controlled the upper chamber before the election, although Prime Minister Shigeru Ishiba, hit by low public support amid daunting challenges, such as rising prices and hefty US tariffs, has described it as not an easy undertaking.

In the October 2024 general election, the ruling coalition lost its majority in the more powerful House of Representatives, or the lower house, forcing Ishiba to form Japan's first minority government in over three decades.

If the ruling coalition fails to hold onto an upper house majority this time, it will become extremely difficult for Ishiba to continue managing his administration, local media reported.