Short version: the best sushi in Boulder, and some of the best I’ve had outside of Japan. Of course, I’ve never been to San Francisco.
For being so scarily landlocked, Boulder has a lot of sushi places. The marvels of modern air travel and refrigeration, of course, but this place has specials which are flown in from Tsukiji market. They use actual wasabi (and let me tell you, if you’ve never had real wasabi, but only the doctored horseradish in common use in this country [and indeed, everywhere outside Japan], real wasabi is eye-opening—it’s got an intense-but-short-lived burst of sinus-clearing sharpness). They have excellent service, from Japanese niceities (irasshaimase as you enter, free tea, etc.) to just a universally appealing sense that you are a person and they are a person and they will treat you well, and you will be glad to return.
There’s not too much I can really say about Japanese food—in fact, less, the better it is. The food at Sushi Tora is made with an elegant simplicity (but look out for the mayonnaise in the California rolls—it’s a thing they do out in this part of the country, apparently? But you can always ask for real crab and no mayo) and in a pleasingly sunlit and calming atmosphere. It’s a bit expensive, but when you want great Japanese, and to not have to think about it, but just let it make you sit up straighter in your seat and half-long for a zabuton rather than a chair, it’s the place.