If you don't want to take IGP metric into account then the easiest way is probably to add communities (via import policy on your eBGP neighbors) and then use those communities differently in iBGP import policy on your other routers.
>>> Because there are the same igp metric and local preference for google routes learning from Hong Kong and Japan.
In this case I believe there is no way to differentiate those routes on different POPs other than using communities. Just add one community to routes received from HK, say 64512:1, and another to routes received from Japan, say 64512:2 in the eBGP import policy and then use them differently to change local preference in iBGP import policy on POPs.
metric is the MED value and metric2 is IGP metric so that is not going to help you with your scenario. You need to use communities and local-preference as other people who have responded are suggesting. It would be something like this: