Level passwords:
The second option on the title screen takes you to the password input. The actual passwords are in Japanese symbols, so here is their description in terms of 'rows' and 'columns' (as they are shown on the Password screen), where e.g. the sixth symbol from the left in the third row would be named "r3c6". All passwords let you start with the highest possible starting stats of 5 HP, 500 sec time and the long rainbow attack, but zero points.
Effect Password
Level 1 Start the game giving an age of less than 5 or above 35
Level 2 r4c6 r2c2 r1c2 r3c10
Level 3 r4c1 r1c2 r4c6 r2c2
Level 4 r3c7 r4c3 r3c6 r3c9
Level 5 r1c5 r3c2 r1c11 r2c5
Level 6 r2c1 r3c3 r4c4 r4c9
Level 7 r1c4 r2c3 r1c12 r1c1
Special Passwords:
Enter these Japanese syllables at the password screen for the named effects.
Effect Password
Boss Minigame #1 E A Wa Se
Boss Minigame #2 Su Mo U Ki
Boss Minigame #3 Su Mo U Shi
Instant Death Shi N N N
Invulnerable Mu Te Ki Sa