Miso soup?

3 Cups Dashi Soup Stock (comes like boullion- prepare with water as noted on the bottle or 1 tsp to 1 cup
3-4 TBSP Miso Paste (any color)
1/4 cup green onion, chopped
*Optional- tofu cubes, seaweed, mushrooms/fungi or pork

Bring Dashi stock to a boil. Reduce heat to simmer. (Add tofu here, or nori or Ladle out 1/2 cup of the stock and dissolve the Miso paste into the hot liquid. Return the miso/dashi mix to the pan and turn the heat completely off. Don't boil the soup once the Miso has been added to it. Serve hot!

I like to make my own dashi without bonito flakes. I usually use dried shiitake mushrooms and wakame seaweed (both are available online). I add fresh miso at the end, so that the heat doesn't kill too many of the healthful enzymes. My favorite miso is South River sweet white miso. I like it because it tastes great, comes in a glass jar, and it is lower in sodium than some other brands. If you can't find seaweed for your miso, add some interesting veggies you like. I vouch for scallions.

As for other low-calorie Japanese foods: I love carrot and daikon (Asian white radish) salad with a light dressing made with mirin and rice vinegar.