Cook the rice according to the package instructions. .
To make the pickled cucumbers, lay the sliced cucumbers in a single layer on a sheet pan and sprinkle with salt. Allow cucumbers to sit for 20 minutes and then pat dry with paper towels. Place the sugar and vinegar in a medium bowl and whisk until the sugar is completely dissolved. Fold in the cucumbers and reserve for use.
Make the octo vinaigrette by mixing all the ingredients together until the sugar is totally dissolved. Season to taste.
Once the rice has cooled, fold in the carrots, green onions, edamame, and octo dressing.
To serve, divide the gaba rice salad between bowls and top with pickled cucumbers. Garnish with butter lettuce leaves.