Yeah, Nishiki was a brand name created by an American firm (West Coast Cycles) to sell imported frames and completes. Nishiki was one of several badges WCC used to market frames, and I'm pretty sure it was, by far, the most successful in terms of sales volume. From the 60's til the mid/late 80s, Nishiki-badged bikes were built by Kawamura in Japan, and quality ranged from pretty low to top-shelf, depending on price point. After the problems with the yen in the 80s, WCC turned to Giant in Taiwan to make the frames for Nishiki bikes, and imo, the quality wasn't as good. By 1990, WCC had sold out to Derby, and Giant continued to build the frames until Derby retired the Nishiki name around y2k. Recently, ....'s Sporting Goods bought the rights to the name, and has been selling Nishiki-badged bikes at their stores. I think the ....'s Nishikis are produced in China.
I've seen Nishikis with Campy drop outs, quad-butted tubing, full Dura-Ace or Campy Record groups, etc.... really high-end bikes. And, i've seen Nishikis that were just a few clicks up from WalMart-level quality. It's going to depend a lot on when and where the bike was made, and what the original MSRP was. I will say that the low-end, cheaper early bikes made by Kawamura were heavy and often wore clunky components, but they were solid and dependable. Later Giant-built cheaper Nishikis tended to be far jenkier.
You got pics of the bike? You said "springer", which makes me think "Cruiser". I'm curious to see whatcha got.