I seriously considered buying a Nishiki bike in the mid-80s but bought a Schwinn LeTour instead.
In the 80s Nishiki made a very good bike.
Here is some information from Sheldon Brown's Nishiki page.
Nishshiki got off to a good start in the U.S. market, but made the error of selling some models to department stores, which created bad feeling against the line among independent bicycle dealers, and they lost a great many dealers as a result of this.
Later, the Nishiki brand became a division of Derby, along with Raleigh and Univega. The Nishiki and Univega names were retired in 2001 so that Derby could concentrate on it's Raleigh brand.
Here is a website I found. Seems they only sell bikes in Europe.
http://www.nishiki.com/startweb.htm