IT guy here. Since I don't know what they actually use as a back-end, I'm going to assume SQL as it's the most common for storing data in similar games. Writing a script to export a player's data to a form that could be easily imported to another server(Think World of Warcraft's character transfer functions) would take a competent programmer a couple days. Said script could be used for anyone willing to pay for a character transfer, as we're sure it wouldn't be free. The bigger problem comes from the fact that most of their services are not supposed to be available outside of Japan, so they probably couldn't offer the option even if they cared enough to write the scripts.