In a medium pot, add enough vegetable oil to fill one and a half an inch. Heat vegetable oil for frying to 350-375 °F.
In a shallow dish, beat the egg with 1 tablespoon of water and set it aside.
Clean each oyster by rinsing under cold water then pat them dry.
Dredge oysters lightly in flour then into the beaten egg. Set oysters on panko breading and gently press them into panko.
Deep fry oysters in oil until lightly browned.
Serve immediately with tonkatsu sauce and a wedge of lemon. Caution: Oyster can be extremely hot.