Is this a bug? I'm interested in flying from Heathrow to Tokyo Haneda and it says route demand is nonexistant... is that right?
That is correct. Haneda is a domestic only airport. There are flights to Seoul Gimpo 4x daily but no flights to Europe.
Also China Airlines use to fly to HND from TPE and HNL in the 1990s. So no demand is correct
I wonder why you even chose Haneda ???
You might fly to Narita instead.