There is no direct mail service from Amazon in Japan to Chinese mainland, which means that unless you have a Japanese friend, send it to him, and then your friend will help you send it back to China.

Otherwise, you can only use the freight forwarding company, that is, if you buy things in Amazon, Japan, and send the address to the freight forwarding company, the freight forwarding company will help you send them back to China, and the freight forwarding company will also send them back to China by express delivery. Different transshipment companies charge different fees. I suggest you look at the charges of the selected transshipment company.

In terms of tariffs, different goods have different tariff rates (it is a random inspection, and if you are lucky, you don't have to pay tariffs).