Don't know the exact answer but when we were there for early dinner several weeks ago, we sat in the dining room but noticed 2 different couples that seemed to walk right over to the sushi bar. Now it's possible they had reservations but it didn't seem that way. It was around 4:00 p.m. and we especially noticed it because my daughter ordered some Japanese pancake-y that she is very familiar with from Japan trips and her Japan students and went bonkers when she saw on the menu. She was told she could go over to the grill to watch it being made (kind of special) and it was where the sushi was being made for those around the bar where we noticed the 2 couples sitting.
PS: It was a lovely dinner and want to go back. Not cheap, however, but nice sushi places aren't.
I also think you could make a reservation for, say, 2 or 4 and when you check in, say you want to sit at the sushi bar. We might actually do that next time as it's fun to be where the action is.