Wash and dry the Persian cucumbers. Slice them into thin rounds or use a vegetable peeler to create long ribbons. Place them in a colander set over a bowl, sprinkle with 1/2 teaspoon of salt, and toss to coat. Let sit for 15-20 minutes to draw out excess water.

After 15-20 minutes, gently pat the cucumbers dry with a paper towel to remove excess moisture and salt. Set aside.

While the cucumbers are sweating, place the well-drained crab meat in a medium bowl. Gently flake it with a fork, keeping some larger chunks. Add half of the Kewpie mayonnaise (1/4 cup), half of the sriracha, and half of the sliced green onions. Gently fold to combine without overmixing.

In a separate small bowl, prepare the dressing. Whisk together the remaining Kewpie mayonnaise (1/4 cup), remaining sriracha, rice vinegar, soy sauce, and toasted sesame oil until smooth and creamy.

In a large serving bowl, combine the dried cucumbers and the spicy crab mixture. Pour the dressing over the top. Add the remaining green onions and the toasted sesame seeds.

Gently toss everything together until evenly coated. For the best flavor, cover and chill in the refrigerator for at least 10-15 minutes before serving.