Uh, before you show up at the NRT lounge, lounge pass in hand, you might want to confirm that the lounge pass is valid there. Why I mention this is that the WC lounge passes I'm familiar with (such as the one that came as a freebie last year with my WC elite card, and those sold by NW, below) are only valid at certain US locations.
From the
WorldClubs Day Pass page on the NWA website:
WorldClubs Day Passes are accepted at any Northwest Airlines-operated WorldClubs in the following 14 U.S. Cities:
* Boston
* Honolulu
* Milwaukee
* Newark
* Washington Dulles
* Chicago-O'Hare
* Los Angeles
* Minneapolis/St. Paul
* Portland
* Washington National/Ronald Reagan
* Detroit
* Memphis
* New York City - LaGuardia
* Seattle/Tacoma