In restaurants that specialize in yakiniku or nabe (hot pot), or serve course meals, even if the menu lists the price per person, there may be a two-person minimum order. The menu might display a photo of the meal, but often the photo shows the volume shared by a certain number of people. Read the menu explanation carefully to confirm whether or not there is a minimum order. Then, if you find that the restaurant made a mistake, you can tell them.