I passed through KIX a few months ago. In the building where the trains depart and beyond, there are a bunch of restaurants but during the afternoon, pretty much all of them were closed (we had 45 mins to wait for the next Haruka so did a bit of an explore). Some did open for dinner. It was all a bit depressing, made me wonder if business is down at KIX.

So I'd suggest you stick to the terminal buildings in your search, no need to wander in the direction of the train stations.