Hi Taffy,
The costs for Japan main tour have decreased year on year, mainly due to the advantageous exchange rate with the YEN at present.
Unfortunately Hong Kong has not benefitted in the same way.
As you can imagine, a considerable part of our add-on costs is the flights. Usually these increase year on year. Without the exchange rate saving of the main tour for Japan this has meant that the main tour decreases in cost, but the add-on increases. I believe there are some dates which have decreased when taking both the add-on and main tour – Sept and October 2016 to name specific departures have both reduced by £200 (compared to 2015) when taking the add-on.
I hope this helps and if you need any more information, please do not hesitate to ask.
Kindest Regards,
Monty