By Tim Kelly and Mariko Katsumura TOKYO (Reuters) -Japanese voters headed to the polls on Sunday in a tightly contested upper house election that could unleash political turmoil, with rising prices and immigration concerns threatening to weaken Prime Minister Shigeru Ishiba's grip on power.

Shigeru Ishiba likes the nitty gritty of policy and making military models, but his dream job as Japanese prime minister looked at risk of coming unstuck on Sunday.

Japanese voters are participating in a crucial upper house election that could determine the fate of Prime Minister Shigeru Ishiba's leadership amidst rising inflation and trade tensions with the US.

Japanese Prime Minister Shigeru Ishiba's coalition lost its upper house majority in elections on Sunday, local media projected, in a result that could end his premiership.