Where is the location?
I bought a SIM card at the airport in Hong Kong.
This is a China Mobile SIM. It is located on the arrival floor next to Travelex (currency exchange shop) and Seven.
I bought a 5-day $80 SIM. It can be used for phone number authentication. The Jungang SIM cannot be used for phone number authentication, so you can use this SIM card when you need to authenticate something.
When I asked the clerk, he opened my phone and set it up for me. The store is small, so it feels cramped when there are three customers.
You can also buy it at Amazon.com in Japan, although it is a bit more expensive. Please refer to this page for more information.
You can buy a SIM card anywhere in Hong Kong, except at the airport. When I went to a store in the city to recharge it later, I was told that it would be cheaper to buy a new one. It may be cheaper to buy a new one depending on the period.
Official Web Site
China Mobile
https://www.hk.chinamobile.com/tc/