Char-grilled? Burger King releases 'black burger' in Japan

Burger King's black burger
Burger King's black burger

In a country renowned for its technological innovations and food, it probably comes as no surprise that the Japanese Burger King menu might throw up a few surprises. But travelers journeying to Tokyo this September might be a little shocked to find out what is on offer.

The Kuro Burger, with "kuro" meaning "black" in Japanese, will be available for a limited period in what the company describes as a chance to "overturn the fast food industry." What's undeniably striking about these cheeseburgers is that they come with black buns, black cheese and black sauce and are effectively a "black burger."

Read MoreBuffett greases $11B Burger King-Tim Hortons deal

The bread is colored with bamboo charcoal and the ketchup – with onion and garlic in a soy sauce base - has squid ink added to it. Not to be outdone, the cheese slices also have bamboo charcoal and naturally the 115 gram beef patties are made with black pepper.

Burger King Japan

The more basic Kuro Pearl burger, including cheese and sauce, will be available for 480 yen ($4.49) while the Kuro Diamond, which includes more normal-looking lettuce, tomato, onion and mayonnaise, will cost 690 yen ($6.45).

Read MoreHow Burger King can avoid a brand backlash

The burger was originally unveiled in 2012, according to a press release on the Burger King Japan website on Wednesday, but its success meant that new upgrades have been added over the years and the latest incarnation adds the black cheese to the bun and the sauce. The offer is scheduled to end in early November.

Releasing images of the burger on its Facebook site, the new addition to the menu received a very mixed reception from fans of the U.S. fast food chain worldwide. One dubbed it the "goth burger" while others were adamant that it should be imported to menus in the United States.

Read MoreDigital dining: Tech revolutions in the food industry

"I wish fast food here were that gourmet," Catherine Chang from San Francisco said on the social network site. Another commenter questioned whether the black coloring was actually a burger that had been overzealously grilled.