Have the miso soup as an appetizer. Miso soup is low in calorie and very tasty. What kind of Japanese restaurant are you going to ? Is the menu online ? If so, why not check the menu to see what sorts of options there are.
If you're going to a "steak" type place, just be mindful of your portion sizes. Sushi is pretty low calorie as long as you watch how many pieces you eat.
Japanese noodle soups like Udon is pretty yummy. There are also Japanese burgers. I've been to a local Japanese burger place that's really good. portions are outrageous. I always take home a doogie bag.
My advice ? Try something that you think you'll enjoy. Don't eat something just because it's low calorie. If the portion size is large, eat half there and take half home to enjoy later.
Edited by: ARCHIMEDESII at: 4/19/2013 (12:55)