From the last Producer Letter

Q12: Are you planning to have a world transfer service?

A12: As this is a game with world barriers, we will be preparing this service so you can move to the same world as old friends as well as new people you meet and become friends with through the Duty Finder. We plan on starting this fee-based service that will allow you to transfer to the world of your choice around 2-3 weeks after launch. Once we have finalized the details we will be sure to let you know.