Kaki-Goya is usually a little restaurant or tent offering grilled oysters and other seafood where you get to cook your own over the grill. Many places also allow you to bring your own drinks.
I was on a recent trip to Isahaya in Nagasaki managed to try the Kaki-yaki (Grilled Oyster) at a Kaki-Goya. Each Kaki-Goya offers various side dishes such as scallops, squid, shell abalone, fresh prawn, etc. I have wanted to try it for years. These are usually only in season from October to end of March so you have to visit at the right time. I had excellent company and the food and drinks was everything that I expected it to be!
I would like to try this place next time!