I had the distinct pleasure of spending a weekend in Vegas with a bunch of guys who were a little more health conscious than the regular "let's party like we're 21 even though we're not!" crowd. I have never partied so well, had so much fun, and felt so good. A lot of it had to do with being pressured to stay totally hydrated so we wouldn't fade at 4am. A lot more had to do with just eating healthy, rather than pigging out on junk.
One of our meals was at j-pop -- we were staying in the Mandalay, it was easy and convenient. We sat at the sushi bar, as it was easy for 8 guys to sit down, order for themselves, pay for themselves, and get rapid, attentive service. Which we did.
I ordered mostly Nigiri. My bro ordered a roll I think. I also had green tea. The fish was good; fresh and flavorful. The chefs made it promptly, and the presentation was excellent. I was hungry from hanging out on the Mandalay Bay Beach, body surfing in their wave pool, and talking to random people, so it was nice to get served up quickly.
It may have been a bit pricey, I don't remember, but seriously what now isn't pricey in LV? Hard to find good food for cheap anymore.