Wagyu simply means Japanese (Wa) cattle (gyu). The farmers rely on hormones and grains to bulk up their cattle with a resulting softness of the sub-cutaneous pure white fat. The average Wagyu steer carcass contains about 35% fat, in some cases fat can constitute more than 40% of the carcass. 
The cattle even get beer to stimulate their appetite whilst simultaneously deliberately restricting their exercise to prevent muscle toughness. http://www.luciesfarm.com/artman/publish/article_39.shtml
Eat Your Greens
Farmers who engage in the practice of raising their livestock on grass get more beef per pound compared with grain fed livestock since the grain fed livestock end up with significantly more fat than those which are able to eat grass.
How To Be Leaner – Eat Greens, not Grains
When you eat a lot of grains you are continuously spiking your blood sugar levels, which then stimulates your appetite so that you eat more. What’s worse is that you never feel as satiated compared to eating good fats, proteins and vegetables. As a result you then consume more throughout the day. To be leaner, like the grass fed cows, eat your greens, do some exercise and leave the grains for the Wagyu. 
The Final Word: “Let food be your medicine and medicine be your food.” Hippocrates circa 400 BC
Primed for Your Life 