Hi-
Sorry to say places in Nagoya that cater to non-Japanese speakers aren't very well known. Asian Mystique.com doesn't have any girls in Nagoya currently, and the only other place I know of is basically an L1 place that will send a girl to your hotel. They used to advertise here:
http://www.erotic-massage-nagoya.com
I can't speak to the quality of their services, because I think the price is way too expensive for what you get.
Other than that, if you feel adventurous, there's a red light district with some soaplands west of Nagoya station, but whether any of those establishments will let you in or what the price/quality is, I can't say. I would also recommend checking out the International Sex Guide website, as they often have some information. Sorry I can't be of more help- if you are in Tokyo at all let me know, I'm far more familiar with the offerings there, and there's plenty of places that will see non-Japanese speakers. Happy hobbying.