These are just a few things you may want to consider when visiting a Volks store in Japan.
1. FCS is Japan Only
Ordering FCS is limited to people who have a Japanese address. FCS orders take 1-2 months to be completed, and Volks do not ship them overseas. If you don't have a Japanese address, you can't place an FCS order. However, if you are visiting on vacation but still want to place an order, you can probably get away with it if you have a friend with a Japanese address. This is technically against the rules but the Volks staff tend to be happy to oblige. You will probably want to have someone with at least a little Japanese go with you to explain, and will also need to take the name, address and phone number of your person in Japan with you.
Note that FCS is pretty much the only thing limited to being Japan only -- anything else that is in stock at the stores you can buy and take home with you. It's only services that require later shipping that are limited to Japanese residents.
2. Volks Events
Not only are there the traditional Volks Dolpas and their After Events, but Volks holds a lot of small events at their stores throughout the year, such as New Outfit Fairs and Sumika Fairs. If your trip coincides with these sort of events then you have the fun added chance of taking part in an event and getting a first chance to see/purchase something new. Make sure to check the Volks website or your favourite BJD news site before you go! Consider the following list:
Tokyo Dolpas: May and December, with After Events roughly 3-4 weeks after
Hometown Dolpas: March and August, with After Events roughly 3-4 weeks after
Tenshi-no-Sato Events: March and October
Tenshi-no-Sumika Fair: September
New Outfit Fairs: every 2-3 months (tends to be fairly random)
3. Using Your Credit Card
If you are planning to go to Volks and spend up big on your credit card, make absolutely sure that you call your credit card company before you leave your country, and inform them that you will be overseas. If you don't let them know, there is the possibility that your credit card charges may be denied. (Due to sudden large purchases appearing from a different country.) The last thing that you want is to get all excited about the things you can buy, only to have your card declined at the cash register!
Note that if you forget to do this and the card is declined, you can still call the credit card company from Japan and ask them to approve it, so don't completely despair. However you'll have to explain this to the Volks staff and see if you can do so in store or not, and it may end up being quite a big confusion for everyone involved, so it's safer to do it in advance!
If there's anything else that you think should be added to this list, don't hesitate to drop me a line
and let me know!