Tenso is an international shipping service from Japan. Not all retailers in Japan will ship internationally and services like Tenso exist to bridge the gap, allowing international customers to still purchase products from Japan. Others exist but Tenso is the most suitable as it connects straight to A!Smart and also connects you to Buyee.
Tenso has their website available in multiple languages and the link above on the logo links straight to the English site. They also provide email support in English and Chinese. Since the site is in English, signing up should be relatively simple. You will need to provide a form of ID to verify your account.
However if you do not use your real name to shop online, you can contact Tenso and have the name you do use added to the account.
Once you have signed up for Tenso, for A!Smart you will only need your Tenso number, but some other sites will need you to input the address manually, such as Tower Records and Universal Music Store.
Tenso have provided a General Guide for this, but I will give a more direct guide on exactly where to stick what parts of the address where for each store.
Once your products arrive at Tenso, they will notify you by email that they have received a package. If you have multiple packages coming in, you may want to wait for all to arrive so you can consolidate those parcels and have them sent in one. This will reduce the cost of shipping slightly.
When you first log in, you will see your parcel waiting in the International Shipping field.