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If you search for "Wellington Restaurants", do you get local results for Wellington NZ, or Wellington in Florida?
You can force NZ results by appending &gl=nz to the search querystring, this shows results for NZ even when searching on google.com
How about adding site:.nz to a search this forces just .nz (including all second level domains such as .co.nz) sites to show.
...but other than that I see no reason for my being shown Japanese results...