Recent remarks by Osaka Mayor Toru Hashimoto justifying the Imperial Japanese Army's "comfort women" brothel system have upset relations with the United States and South Korea and enraged human rights activists both at home and abroad.

The impact on domestic politics has also been great, as major parties distance themselves from Hashimoto's Nippon Ishin no Kai (Japan Restoration Party). Right-leaning politicians, including Prime Minister Shinzo Abe, also now find it harder to address historical issues, including the comfort women, Japan's euphemism for the wartime sex slaves.

Polls show support for Nippon Ishin, which Hashimoto is a coleader of, have plummeted, clouding the party's prospects for the Upper House election in July and the Tokyo Metropolitan Assembly election in June.