Curry rice is extremely popular in Japan. In fact according to the Japanese food giant House-Foods, Curry can be considered a Japanese national dish similar to ramen. You will be able to find curry being offered in most Japanese diner menu next to oyakodon, ramen, and other traditional Japanese food. This following curry recipe requires Japanese curry roux. All the curry spices are in a form of solid roux resembling a block of baking chocolate. Japanese curry spice is different from Thai or Indian curry, so I'd recommend you to buy the roux from Japanese supermarket or an Asian food isle in your local grocery store (they usually have it). I always add other ingredients so my curry doesn't taste "out of box". I hope you like Japanese curry!