Despite being Japan's most densely populated area, Warabi rarely causes a blip on the national media radar.

Set in a rusting corner of Saitama Prefecture, the city has two minor recent claims to fame: a communist mayor and the 13-year-old daughter of illegal Filipino immigrants.

An odd place perhaps for two groups with radically different visions of Japan to take to the streets, but this is where neo-nationalists and liberal opponents could be found slugging it out last weekend.