Soak onions in a bowl of water for 10 minutes and drain the water. Set aside.
Take the yakisoba out of the packaging and place on a microwave-safe plate. Lightly cover with a plastic wrap and microwave for 1 minute.
Once the noodles cool down, cut the noodles to bite sizes (see photo below). Place the noodles in a bowl and add lemon juice while loosening the noodles. Mix in the imitation crabs, cucumbers, onions, mayonnaise, and adjust to taste with salt and pepper.
Place the salad in a bowl/plate, garnish with parsley, and you are done!