Mayor Osami Takeyama's victory Sunday in the Sakai mayoral election in Osaka Prefecture has cast a shadow over the political future of brash Nippon Ishin co-leader Toru Hashimoto, the mayor of Osaka.

Takeyama, a 63-year-old independent, defeated former Sakai Assemblyman Katsutoshi Nishibayashi, his sole challenger, with the backing of the Democratic Party of Japan and the ruling Liberal Democratic Party, early returns showed.

Nishibayashi, 43, was backed by Nippon Ishin no Kai (Japan Restoration Party).