At the music board there are three different note visualizations available: by displaying the notes in notes window, bubbles of different colors pop up from the key cursor position and display the rabbits in notes window. Modes can be selected with blue flashing button at the top-right. Select the bubbles mode (slow flashing blue bubble, once pressed), then hold Right then press Start to switch bubbles to alphabet letters.
Color Chooser
At the title screen, press A, A, B, B, Right, Left and Select. If done right, the word "BOY" will appear on the top left of the screen. Change it to select from multiple color schemes.
Hidden Song
Start the game, press A, select Japan, now press Select 2 times to go back to the music board. On the music board, hold the A button and press Up multiple times to hear a hidden song.
Music Speed Select
At the music board, put the cursor at the speed multiplier, then hold Down and press Start to set the music speed at half the normal. Press and hold Up on any music board control and press Start to return speed back to normal.
Alternate Note Visualization...