Porcelain or Ceramic Coach

This was given to me when I was 16 from my grandmother who was about 67 at the time. She was given it by a elderly lady she worked for with a strict understanding that it was not to be sold. When she handed it to me she gave me the same instruction. I don't know why and neither did she maybe it meant something to the lady for someone to love it. I truly do and it may be one of two things I still have in my life since I was 16 years old. What makes me post this is I would like to know if it is part of a set? What type of set? Seems like it could be to hold cotton balls on a vanity or maybe hold sugar cubes on the tea table? That is just speculation though and I would like to know the facts. So if you hold a portion of the set to this or a whole one WOW tell me about it and how you use it. (sorry about photos cell camera) **On the bottom of the coach it says "hand painted Made in Japan" and has the Great Wall painted on it.