The grading system is regulated by the Japan Meat Grading Association that is authorized by the Japanese government.  There are two categories to grade the carcasses.

1) Yield Grade: A to C

2) Meat Quality Grade: 1-5 (5 is the highest).

Yield subjects the final meat ratio.  A is the highest and means above average.  B means average, and C means below average.

For the Meat Quality Grading, they are evaluated on four points: marbling; color and shine of meat; firmness and texture; and fat color and shine.  They strictly check one by one -- almost like a beauty contest!  The aesthetics of color is an essential part of grading.  Therefore the famous A5 is the best of the best.