Unlock All Songs:
Select "Credits" in the "Options" menu. Then, quickly press Up, Up, Down, Down, Left, Right, Left, Right, B, A, Up, Up, Down, Down, Left, Right, Left, Right, A, B on a controller plugged into port four.
Unlock Konsento:03 and Maid-Zukin dancers:
Select "Dancers" in the "Options" menu. Then, hold X + Y on controller four until you hear a sound confirming it. In Xbox Live, you must do this everytime you want to use these dancers unless you purchase them.
Thanks to Revolution Reader wombat_xing!