The burgers are only available in Japan, for now, which actually might make them less gross than if they had been released in America. I'm guessing an American version would be made black with food coloring, but the Japanese version uses some pretty creative methods to come up with pigmentation for this burger:
buns & cheese: smoked with bamboo charcoal
sauce: onion, garlic, and squid ink
I'd try it. But it is weird. Very weird. The cheese slices look like bits of visqueen when they are all piled up: