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.