Hayato Shimizu, supported by the Democratic Party of Japan, won a landslide victory in the May 24 mayoral election in the city of Saitama, beating five rivals, including the incumbent backed by the ruling camp.

The election was closely watched as the first major local election since Yukio Hatoyama took over as DPJ president in early May from Ichiro Ozawa, who resigned over a fundraising scandal involving his top secretary.

Shimizu's victory gives the DPJ a boost heading into the general election that must be held before October and deals a blow to Prime Minister Taro Aso, whose Cabinet is suffering low public support ratings.

"I hope the change of power in Saitama will lead to political reform in all of Japan," Shimizu said May 24.