From day one, we tried to expose them to as much outside culture as we could. We didn't have the time to take them on two week jaunts to Japan, but we went for more accessible places. Fortunately, Germany is a country with other lands close by. We regularly took them to the Netherlands, Belgium, and Switzerland. There were occasional visits to Spain and Denmark, and my younger daughter spent a semester of college in France, as well as a stay in Sierra Leone with the U.N. War Crimes Tribunal. That last was hardly a vacation, but it was certainly part of her education. They have also been to the Maldives and Israel, places I have not seen.
Growing up in Europe, especially with parents from two different countries and languages, gives children the chance (no guarantees!) that they will grow up aware and tolerant of other cultures, and that was certainly our goal. Whether the grandchildren actually develop an affinity with and for Japan is really secondary, as long as they retain a latent knowledge that there ARE such places out there, and that the vast majority of people on this earth are not like they are.