Hi Juro -
Actually, it wasn't the greatest - fresh of course, but I think the farm raised fish don't taste as nice! Not one of my favorites (like you I prefer Bonito and Yellowtail tuna), but very fresh at least. I made sashimi once from a 34" last year that someone caught and gave to me while I was just learning to flyfish (he got it on a yellow Rebel). Now THAT tasted great!
My first taste of sushi was in Japan and I haven't been able to stop since - although my thinning wallet will stop it soon!
I was surprised to find very little in the way of sushi on the cape - we had to go from Chatham to Hyannis for the closest decent stuff (quite decent actually).