Nihon gyu, is graded in part according to the fat’s marbling and this is what we refer to as Shimofuri. The grading of beef is categorized by the weight of the carcass to the ratio of trimmed meat. The beef marbling, color, firmness and texture and fat color and quality are all integral.

The yield grade is made up of 15 grades and A5 being the highest marbling. But having said that, I am not a big fan of fat unless it is consistent and striated. This is a list of exported beef from Japan.

http://www.kobe-niku.jp/contents/export/index.php?y=2013&page=1