The Kuro Pearl and Kuro Ninja burgers also contain squid ink.
Burger King in Japan is taking bizarre fast food to new heights with black cheeseburgers complete with black buns, black cheese and black sauce.
The chain started the Premium Kuro Burger (kuro means “black”) in 2012, colouring the bread with bamboo charcoal and adding squid ink to the ketchup.
Last year it evolved to the Kuro Ninja, which had all the above with a slice of bacon for a tongue, and now Burger King is on the third generation.
Apparently Japanese customers quite liked the bamboo charcoal, so it is now in the cheese slices as well, along with beef burgers made with black pepper, an onion and garlic sauce with squid ink and the black bread.
While the smaller Kuro Pearl contains the burger, cheese and sauce, the upgraded Kuro Diamond also comes with more edible-looking lettuce, tomato, onion and the usual trimmings.
Kuro processed cheese slices, made with bamboo charcoal
A press release from Burger King Japan said there had been a “favourable reception” to previous Kuro burgers, which have all be limited editions.
The current inventions will be available from 19 September, with the Kuro Pearl priced at 480 yen (£2.80) and the Kuro Diamond at (£4.00).
Black buns been seen before, when rivals McDonald’s released “ying and yang” style burgers in China.
Chinese bloggers reasoned that the concept came from a proverb about black and white representing good and evil in society.