The Japanese love to deep-fry their food to the point that many izakaya propose full deep-fried food sets including vegetables and seafood and the ubiquitous prawns.
The Japanese will usually utilize kuruma ebi/Imperial prawns or Black Tiger variety for the latter.
There is nothing complicated about preparing deep-fried prawns. The key is to use fresh ingredients and serve as soon as ready.

INGREDIENTS:

-Imperial Prawns/Black Tiger Prawns
-Salt and pepper: to taste
-All-purpose flour
-Egg (s)
-Breadcrumbs or panko (the rough style). Real fresh breadcrumbs are the best.
-Tartare sauce for serving. or tare/bulldog sauce and mustard.

RECIPE:

If the prawn is absolutely fresh take the shell off leaving the head and tail on.
If not, tail the head off but leave the tail on for “handling” when eating it.

Take off the innards with a toothpick by inserting under and pulling it out. Don’t worry about “breaking the back” of the prawn. Actually this is the trick which prevents the prawn from from bending upon frying!

Actually, continue with the trick by making a few shallow cuts acrosss the back of the prawn to make sure it will not bend at all!
Sprinkle with salt (a little only!) and pepper to taste.

Roll prawns in flour.

Then in the beaten eggs.

Apply plenty of breadcrumbs/panko all over the prawns, head and tail included. Pat them lightly between you palms to help breadcrumbs to adhere.

Heat the oil at 170 degrees (less is unsuitable, 180 degrees is the very maximum). Drop the prawns gently into the oil head first.
Avoid manipulating them while frying.
Don’t fry too many at one time as the temperature of the oil will suddenly decrease.
Take them out with chopsticks. Place them on a grill for a few seconds to get rid of excess oil.
Serve with sauce and eat at once!