juicyjuju-
The alternative restaurants, Prego and Kyoto are not open for lunch. We did not try the sushi at dinner. However, if you ask the day before, that you would like sushi for lunch the next day in the main dining room, chances are you will get it. In the main dining room they try to cater to your every whim. Normally, if you give them one days notice, you will have what you want the next day.
Have a wonderful cruise.