How to differentiate your burger in a world of endless offerings? Burger King Japan thinks it has the answer: turn it a strange color for novelty value. The Japanese arm of the fast food giant has launched two burgers, the Kuro Pearl and the Kuro Diamond, that not only have black buns (which BK Japan first introduced in 2012), but black cheese and black "ketchup" inside them. The cheese is made with bamboo charcoal and the ketchup is an onion-and-garlic sauce made with squid ink. The design move is making waves outside Japan; the black burgers have quickly caught the attention of the world's media, with Time, The Guardian, USA Today and others reporting the launch.