Gettting to Tonga

Can anyone tell me please If I can fly to Nuku'alofa from Asia?

Thanks in Advance

Of course you can, but not directly.
You must fly via Australia, New Zealand or (from Hong Kong only) via Fiji.

Thanks, which airline is it from Hong Kong please?

Fiji's Air Pacific - meaning you can kind of feel in the South Pacific as soon as you step aboard the plane in HK! :-)
The same airline will fly you on to Tonga, and you could have a stopover in Fiji if you want.