Once you completed the game for the first time, the following secrets will be available after you saved your game clear data which the save file will have a star in it.

Unlockable	How to Unlock
EX New Game	After creating a game clear data, the "EX New Game" selection will now be accessible where a game clear data is required to get this to work.
Grade Shop	Once you loaded your game clear data in "EX New Game", the Grade Shop will be available each time you start a new game in this mode.
Nam Cobanda Isle	This area will be available after you load your game clear data. You'll find it on the northwest end of the world map.
Unknown Difficulty	In the Grade Shop, purchase "Battle Rank" for 50 Grade points.