As I wrote in the Beef Curry recipe, I don't make my own curry powder. Lomo asked in the comments about the "secret" 15 to 20 spices that make up curry powder. After poking around a bit on Japanese web sites, I came up with this page that describes what goes into S & B curry powders, the most popular brand by far in Japan. It's an official S & B page, so should be accurate,