All orders to European countries are subject to import duties, but they sometimes aren't taxed. This is largely left up to each country and its customs authority.
If you want to avoid import duties, the best option is to use Japan Post, though you might still be liable for import duties. Shipping through Yamato/UPS to Europe and some other countries will likely incur a large amount of import duties. Please only select Yamato/UPS if you are willing to pay these extra import duties.
France charges extra import duties on all packages sent express. It appears that the UK doesn't charge these additional fees.
Please message us right after placing your order (or in a note when placing your order) to state that you want the slower Japan Post shipping method if your order is scheduled to be shipped through Yamato Transport.
Orders to the U.S., Mexico, Australia, and a few other countries aren't subject to any import duties.