A considerable number of Japanese businesses operating in Europe are concentrated in the UK. We have been informed of a variety of requests that these businesses have in relation to BREXIT including: maintenance of trade in goods with no burdens of customs duties and procedures; unfettered investment; maintenance of an environment in which services and financial transactions across Europe can be provided and carried out smoothly; access to workforces with the necessary skills; and harmonised regulations and standards between the UK and the EU.
The Government of Japan trusts that the UK and the EU, by heeding such requests to the fullest extent and responding to them in a cooperative manner, will maintain the current business environment or alleviate the impacts of any radical changes, so as to remain an attractive destination for doing business.
This is just from the introduction. The body of the 15 page document gets into a lot more detail about the potential cost of Brexit to Japanese businesses.
Free movement of people is explicit in the demands here and it is also implicit in the demand to maintain full access to the single market as well. It isn’t hard to imagine what is going to happen if the UK does not opt for an EEA style outcome preserving that free movement. Japanese companies are estimated directly to employ around 140,000 skilled, well paid, unionised British workers. There must be thousands more in related jobs further along the supply chain and in related services, never mind all the spending of those workers in their local shops. Multiply that up as other foreign investors also pull out.
Full 15 page source document: Japan’s Message to the United Kingdom and the European Union