This place has been around for years. (It's the one next to Fort Saint George - I was a somewhat regular between 2005 and 2008).
My recollection is that it was much more authentic than some of the places that came later (e.g. Wann in belltown) but really suffers by comparison to what's available in Vancouver, BC.
BTW, I love Fort Saint George. Absolutely no attempt to cater to western ideas of Japanese food, it's actually a yoshoku restaurant serving Japanized western dishes to a mostly jp expat crowd - omuraisu, kareraisu, doria, hamburger steak with grated radish, etc.