Actually they did fly JFK-KIX nonstop four or five times weekly in the early Ninties,at one point the flight continued on to Sydney(747-400 while JFK-NRT was a 747-200).
It was at a time when NW was making a push in Australia with nonstop flights from LAX,HNL and KIX to Brisbane,Sydney and Melbourne.
The Japanese and Australians made a big fuss over the fact that NW was picking up alot of Japanese passengers in Japan for their KIX-SYD flights.
The early Ninties saw Continental,NW and UAL competing in the US-Australian market,however NW pulled out around '92 and Continental around '93.
Eastern Air lines flt # 701, EWR-MCO Boeing 757