Bonus levels 

During a level, collect all six stars to get a doll. After you collect 8 and 16 dolls you'll unlock bonus levels...

Boss battle 

Beat the fairground levels to unlock a new area that allows you to battle previously defeated Bosses.

Music test 

Beat either bonus level to unlock songs in the music box option.

Picture gallery

Beat the fairground levels to unlock a picture gallery.

Unlock Mometsuto

Beat the game to have Mometsuto as a playable character