Mini-store here in Korea are enormous, 24 hours store exactly like Seven/Eleven. In every corner you can find them you are not going to be lost because they are well lighted. So when you are hungry in the middle of the night all you need to do is run the nearest GS25, Family Mart, Seven/Eleven and so on., they cost $2-3 per instant meal it depends in the food.
This is one of my late meal from GS25 bulgogi, quail eggs, fish cake, kimchi and rice. Just heat in the microwave over and ready to eat.