Originally Posted by
Mwenenzi
Also trying with first flight HKG-MEL(on CX) may get a different result, as surcharges cannot be charged in Hong Kong. (CX issued ticket)
AFAIK if your first flight is HKG-MEL on CX you would be charged the HK LONE/DONE base fare, which at least for DONE is significantly higher than that of Japan.
Also, CX does charge a fuel surcharge for itineraries starting outside HK (although not sure about Japan as it is another jurisdiction where fuel surcharge is government regulated.)