Burger King Japan's special sauce for it's black burger is made with onion, garlic and squid ink Burger King Japan

Burger King's black cheese is made with squid ink and bamboo charcoal Burger King Japan

Burger King did it once before, and now the fast food chain is going back in black... but only in Japan.The franchise is rolling out all black burgers for its hungry customers. Burger King Japan confirmed two new black burgers in a press release and also on its Facebook page There's the KURO Pearl which is a whopper pattie with extra black pepper on a black bun, black sauce with strange looking black cheese for $4.49. Add two dollars more, and you can get a bigger black burger topped off with fresh lettuce, tomato, onion and mayonnaise.So what did Burger King do to make all the ingredients so black? The sauce was simple enough. Burger King says it's a delicious combination of onion, garlic and squid ink.Then there's the cheese and buns. Burger King says it created both by smoking normal buns and cheese with bamboo charcoal.Both Burger King and McDonald's have sold burgers with black buns in the past across parts of Japan and China, but this is the first time we've heard of burgers with black cheese too. The burgers go on sale starting next week and will only be available through early November.