A paper trail that runs from Okinawa to Canada and from Israel to Italy and France links some unauthorized online traders on the blacklist of Japan's financial regulator to offshore companies in tax havens, an analysis of files leaked from a Panamanian law firm has revealed.

The documents are part of the Panama Papers, a cache of 11.5 million files obtained by the German newspaper Suddeutsche Zeitung and shared with the International Consortium of Investigative Journalists and their media partners.

At least four binary option trading operators that have received warnings from the Financial Services Agency for targeting Japanese users without proper authorization are connected to companies incorporated through a complex network of offshore shell firms and shareholders, according to the documents.