I've been told that kaitenzushi (rotating sushi) is not generally the best sushi but I personally found almost every kaitenzushi place in Japan to be better than any sushi restaurant I've eaten at in the United States. I tried several of them. My favorites are:
1) The kaitenzushi store in Shinjuku outside the south exit. Exit the station by Tower Records, walk down the stairs and then cross the street and go down the street on the left that cuts away diagonally. The store is on the first block on the left. If you aren't paying attention you can pass it as the stores on that street are so busy. At this store all plates are 120 yen and I was never disappointed with the quality.
2) In Kawasaki there is a store in the outdoor covered mall street near the side closest to Yokohama. I only went there a few times but the thing I liked most was that they seemed to have the most selection. And not just sushi but soups, fruits, desserts. Pretty good.
3) Also in JR Kawasaki station at the bottom of the stairs to the right there is a small kaitenzushi place. They had the best toro sushi, the best kind, I've had at a kaitenzushi store but it was also pretty expensive. If I remember correctly the toro plate was 500 yen.