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. On September 19, Burger King Japan's offerings will include two more Black Burgers, namely Kuro Pearl and Kuro Diamond. These both feature black cheese - made with bamboo charcoal - black-pepper burger, onion and garlic sauce with squid ink and the eye-catching black bun.