Gyudon is a contraction of two Japanese works Gyuniku (beef) and Donburi (rice with a topping). Gyudon is a very popular Japanese meal and there are a few Gyudon chains in Japan. These chains often use very cheap beef, but when my wife makes it (as in this photo) she buys better quality beef, than what the cheap Gyudon chains use. Actually I've also tried more expensive Gyudon at some upmarket restaurants. Something I recommend you try at least once when you come to Japan and not just think of it as a cheep 380yen dish!
From A Stream of Images