Completion bonus
Finish the entire game and save when prompted. Re-load the cleared saved game file. You can start a new game with all previously collected Score Pieces, Party Levels and a Hero's Crest. In the new game session you will be play against more difficult enemies and Bosses.
Echo Meter
Be sure to build up your Echo Meter during each battle so that you can unleash your special attacks with more damage. You build the meter by attacking enemies with your regular attacks, which will build it up to 4 hits, 8 hits, 12 hits, 16 hits, 24 hits, and 32 hits (the latter being the highest). Unleashing special attacks at that plateau will result in the most powerful attacks your characters can use, but be sure to use them in the present battle, because the meter, even if unused, will be reset before the next battle.
New Game +
Complete the game once from your first play and save the data when prompted to. Load that file to begin a new game with all obtained Score Pieces, Party Levels, Piano Music and Hero's Crest. Plus, the enemies and bosses will be much stronger and tougher in battle and you can view the ending anytime after you load the game clear data and choose "View Ending". In addition to the PlayStation 3 version, any costumes you obtained for Polka, Allegretto and Beat will be carried over to the new game.