Enter these in the options screen.

Effect	Password
99 credits	TOMOYO
Change in-game colors	COLORE
Change in-game colors	COLORD
Change in-game colors	COLORC
Change in-game colors	COLORB
Change in-game colors	COLORF
Change in-game colors (restore default value)	COLORA
DEMO-REC mode	OGOSHI
Invert colors	INVERT
Invincible	OHNUKI
Record gameplay	RECORD
Replays recorded gameplay	REPLAY
Stage progress counter	LOCATE
Stage select	SOSITE