The secret on the east coast is that you use lots of rum, but not so much as to overpower it.
My specific question to you, because you are facing a number of obstacles that you almost have to eliminate one at a time, but on your first visit to Japan....
I can tell you, on my first visit to Japan, the whole baking industry in Japan, the sweets, the confectioneries, they take it to a whole other level. It's like walking into a confectionery in Paris. It is absolutely incredible, very high-end, and amazing quality. You have a niche product here that should be able to fit into that marketplace extremely well.