As of July 2017, is Cairns the only place in Australia that is a direct flight to or from the Kansai region? (I've read reports of a seasonal service between KIX and Sydney happening this coming summer)
If so, why aren't there currently any other direct flight destinations, and how do Japanese people and Australians typically go to and from the Kansai region to Sydney and Melbourne?
There seems to be a direct flight between Kansai International Airport and Melboroune Airport operated by Jetstar Airways. However, when I searched for its flights I didn't get any direct flights. So it might be temporarily suspended or no longer operated.
In general Japanese people living outside of Tokyo use 2 or more flights, either domestic or international. They usually fly (or via other transports) to Tokyo (Narita/Haneda), or sometimes Incheon International Airport (South Korea), as it connects well to airports in the countryside in Japan. Kansai International Airport is not that bad in terms of connecting cities, but if they don't find a direct flight, they use a connecting flight.
The "why" is likely just economics.
There is an open skies agreement between Japan and Australia, so limits on how many flights can operate between Kansai & Australian airports should not be a factor.
That leaves the biggest factor in planning what routes to offer - loads. One would have to hazard a guess that not that many passengers leaving Kansai end up connecting to Australia. And not that many passengers flying Australia to Japan connect immediately to Kansai.
As it happens, Qantas has just announced direct flights from Osaka-Kansai to Sydney starting December 2017: http://australianaviation.com.au/2017/07/qantas-returns-to-osaka-kansai-with-seasonal-sydney-services/
The flight will operate three times a week and is initially scheduled as a seasonal service ending in March, but it will likely become permanent if successful.
For time being, travelers from Sydney or Melbourne to Osaka usually fly to Tokyo and take the bullet train the rest of the way.
