Remove skin and bones from chicken; discard skin. Simmer chicken, bones, ginger and salt in the 4 cups of water for 30 minutes; strain broth. Cut chicken into thin slices and place it back into the broth. Put greens into another pot of boiling water for 2 minutes. Drain, rinse in cold water, and drain again. Cut mizuna into 1-inch pieces. Broil mochi until puffed and soft but not brown. Thinly slice bamboo shoot and matsutake lengthwise. Heat broth to simmering temperature. Cook for 15 minutes; skim. Add soy sauce and simmer 1 more minute. Arrange greens, mochi, and the bamboo and matsutake slices in soup bowls. Slowly pour soup over arrangement. Serve immediately. Makes 6 servings.
Approximate Nutrient Analysis per serving:
135 calories, 1 g fat, 0 g saturated fat, 30 mg cholesterol, 600 mg sodium, 18 g carbohydrate, 1.5 g fiber, 1 g sugar, 13 g protein