Depending on whether you are starting a new Reborn campaign, or joining another campaign, there is a roster of characters you can choose from to decide which character to play. 

These are the surviving 'consignments' who were aboard the ill-fated Nova Skimmer when disaster struck. 

When selecting which character to play, you will only be able to access some limited information about the roster of available characters.  Discovering your past, your abilities, and deciding how your 'reborn' character will evolve, are central elements of the game.