The future of Nippon Ishin no Kai (Japan Restoration Party) co-leader Toru Hashimoto remained unclear Sunday evening following the party's poor performance in the Upper House election.

"This isn't a victory. It's not something to be proud of," Hashimoto, also the mayor of Osaka, said during a news conference Sunday evening.

Just four of the party's 44 candidates were assured of winning as of 10 p.m. Former top Nippon Ishin official Toru Azuma, 46, won a seat in Osaka and Takayuki Shimizu, 39, will represent Hyogo. Kyoko Nakayama, 73, was re-elected as a proportional representation candidate. Former professor wrestler and Upper House member Antonio Inoki also snagged a proportional seat.