Stir soy sauce, rice wine, ginger, and garlic together in a shallow dish. Place tuna in the marinade, and turn to coat. Cover dish and refrigerate for at least 30 minutes.
Preheat grill for medium-high heat.
Remove tuna from marinade and discard remaining liquid. Brush both sides of steaks with oil.
Cook tuna on the preheated grill until cooked through, 3 to 6 minutes per side.
