Finding a Sake
taboo, assuming the Sushi Roku to which you refer is the Pasadena restaurant, then the California Department of Alcoholic Beverage Control, http://www.abc.ca.gov/ is your friend -- if you can find anybody at his or her desk during the restricted hours caused by the budget crisis. No alcoholic beverage sold at a public establishment in California has been imported into California without ABC approval, and the name and address of the importer would be a public record.
As a fallback position, you might find other sakés from Fukushima that tickle the same pleasure zones. For instance, Dai Shichi, which generally is credited with reviving the kimoto method of brewing, is from Fukushima, and the saké is outstanding -- and considerably less expensive than Katana Aizu.