The stakes are high for Japan's ruling Democratic Party of Japan (DPJ) in Sunday's upper house elections, as polls opened to voters, dpa reported.
The party and its ally need to win 56 seats to control the chamber.
The DPJ currently holds 116 seats, and its junior partner, the People's New Party (PNP), six seats. Half of the House of Councillors' 242 seats are up for grabs.