Music test:
Successfully complete either bonus level to unlock songs in the music box option.

Boss battle:
Successfully complete the fairground levels to unlock a new area that allows you to battle previously defeated Bosses.

Picture gallery:
Successfully complete the fairground levels to unlock an option for a picture gallery.

Play as Mometsuto:
Successfully complete the game to unlock Mometsuto as a playable character.

Bonus levels:
Collect all six stars in a level to get a doll. A bonus level will be unlocked after you have accumulated eight and sixteen dolls.