I am Cameroonian passport holder living and working in JAPAN.

But this morning I've seen a good product that I would like to acquire from China and according to the seller, they cannot wait for me until I apply for the Visa and the product could be sold anytime.
So I was wondering if there is any possibility for me to use that 72-Hour Free transit to make an Go and return to check the product as advised by the seller?
Regards!