8888 Sevensenses, 888 Cosmo/Life:

Choose CONTINUE on the title screen & enter these hiragana letters :
"shi" (6x), "ze" (2x), "nu" (2x), "wa" (16x), "a" (5x).

Incase you don't know Japanese letters : (I assume all the counts start from the upper left as 1st column & 1st row):
shi : column 2, row 3
ze : column 9, row 4
nu : column 3, row 5
wa : column 9, row 1
a : column 1, row 1

 

9999 Sevensenses, 999 Cosmo/Life:

Choose CONTINUE on the title screen & enter these hiragana letters :
shi (x6) ga (x2) ze (x2) ga (x16) a (x5)
shi column 2 row 3
ga column 6 row 3
ze column 9 row 4
a column 1 row 1

 

Ending Password:

At the password screen, enter the first Japanese character 14 times. Press Down 6 times, Right 3 times and enter the Japanese character 10 times. Press Left 3 times, Up 6 times and enter the Japanese character 2 times. Press Right 4 times, Down 1 time and enter the Japanese character. Press Up 1 time, Left 4 times and enter the Japanese character 3 times. Press Right 4 times, Down 1 time and enter the Japanese character. Now select End to go to the last area where you'll get the ending.

 

Last Stage Password:

At the password screen, enter the following Japanese characters. Format is Row #, Column #: - 5,6 - 7,4 - 4,2 - 6,10 - 7,3 - - 7,3 - 4,2 - 7,3 - 4,1 - 5,1 - 3,6 - 3,1 - - 1,1 - 1,1 - 1,9 - 1,1 - 1,1 - - 1,1 - 4,9 - 1,1 - 1,1 - 1,1 - 4,9 - 1,1 - - 6,4 - 1,6 - 5,5 - 2,5 - 4,7 - 1,3 - 2,7 -