If I can't get it from one of my usual sources, I 'll buy it at the
supermarket. I'll not eat the stuff raw from there though, as it's
usualy not fresh enough. What I do with it though is to make a marinade
of cold dashi, sake, a few drops of shoyu, and fresh lemon juice. Peel
the shrimp and marinate for a few hours. The shrimp get cooked like
escabiche and go really well on a finger of rice.