At the title screen enter the following code:

Up, Up, Down, Down, Left, Right, Left, Right, Circle, X, Start.

Once done, a screen will come up showing ''Extra Option'' where there's a Date set and a Display Mode set

Hold L1 and R1 while selecting Original Mode, and you'll unlock an option to change the music played in the game. This works in Arrange mode, as well.

Enter your name as: NOMIS

Now you will start the game with much less energy than usual. This will make the game much more challenging.