I'd guess a timeframe of about 1977-1980. Japanese built, but the original name on it might have been that of an importer.

In particular, it reminds me of low-mid level Centurions of that period. There are some catalog scans floating around on the web to compare to. Look at the rear brake-cable-hanger. Centurion was an importer, not a manufacturer, so anyone else using the same contract builder in Japan might have gotten the same frames or something similar.

Interesting that the bottom bracket appears to have been replaced in the last ten years or so, but the tires look like they're original!