If Japanese cucumbers are not available, English cucumbers can be substituted. The English cucumbers need to be peeled, cut lengthwise, seeded and sliced into thin half moons. In a large bowl, combine cucumbers and salt and mix well. Add sugar, soy sauce, rice wine vinegar and sesame oil and mix well. Sprinkle with sesame seeds and mix. Let marinate for 20 minutes before serving. Adjust seasonings before serving.