Just when you thought everything that could be done with burgers had been done, Burger King Japan makes these black ones. Facebook: BURGERKINGJP As the press release says, the Kuro (i.e. "black") burger really is on sale in Japan, and comes in two varieties: diamond and pearl.The black colour of the bun is achieved by using bamboo charcoal, and the black sauce is created with squid ink. The Kuro made its first appearance in 2012 (we deemed it one of the year's greatest fast-food inventions), but has been brought back because people actually liked it. The Kuro Pearl could be yours for 480 yen (about £2.76). The press release, when very roughly translated by Google, says it was "baked in juicy straight fire". burgerkingjapan.co.jp The Kuro Diamond is a bit pricier at 690 yen (nearly £4). The press release, when (again) badly translated, says: "Vegetables is also a luxury item that can be firmly taken." burgerkingjapan.co.jp You'd better be quick though: The Kuro is only available on a limited basis.