At a restaurant I asked about the ingredients in a dish on the menu for religious reasons, but they wouldn’t tell me.

For health or religious reasons, it is very important to know what kind of ingredients are in dishes. Also, it would be nice to have the seller to explain politely. But in Japan, awareness of dietary restrictions is still quite low. The restaurant people may not even fully understand whether or not certain ingredients are being used in the food. There is also the possibility that language issues may be interfering with communication. If there are certain things that you absolutely cannot eat, if you have them written on a card in Japanese with the reason why you can’t eat them, this will make it easier for people to give you a clear answer.