What is this thing?
 

So my wife picked up a free bike from the side of the road a couple of years ago and finally has asked for my help with it. But I really don't know what I'm looking at. It's a Nishiki Olympic and the Serial Number is KS 306045. I'd be willing to be it's all original and not in horrible shape. If anyone has a clue what year it's from or how to decode the serial, that would be awesome. She just wants a bike to ride the local rail-trail on with the kids. Any help would be much appreciated.

http://sphotos.ak.fbcdn.net/hphotos-..._4483430_n.jpg