Go  to  the options menu and enter any of the following
passwords at the passwords screen:

Boss Rush mode               Input "MUSEUM" as a password.
Deactivate the all cheats    Input "XXXXXX" as a password.
View creadits                Input "AGES" as a password.
Onchi Music mode and 
credit's music in sound test Input "MAGURO" as a password.
Select any stage             Input "ILOVEU" as a password.
Enable Super Difficulty Mode Input "SUPERB" as a password.
Enable Super Hard mode       Input "SUPER" as a password.
Enable Time Attack mode      Input "DOFEEL" as a password.
Hidden bonuses marked 
by a star                    Input "MIEMIE" as a password.

(JP version):
Reverses the Hi-Score 
in Demo Mode                 Input "HETAP" as a password.
Displays Solar System        Input "VALDI" as a password.
Activate Invincibility       Input "CANDY" as a password.
Mentions Miyake colour       Input "MACCHA" as a password.
Mentions next game           Input "MASTER" as a password.
No Continue limit            Input "AAAAAA" as a password.
A shooting star goes 
across the background        Input "STAR" as a password.
ILOVEU, MIEMIE, CANDY 
active all at once           Input "FEEL" as a password.