A device, including a first storage unit configured to store a first plurality of files and a first management data corresponding to the first files; a connector configured to connect to an external storage device, the external storage being configured to store a second plurality of files and second management data corresponding to the second files; a controller configured to generate new management data by merging the first management data and the second management data, and to store the new management data in a memory; and a display unit configured to display contents of the first and second plurality of files based on the new management data without indicating to the user where the respective files are stored.