Unlocks all the secrets in the game:
Enter R3, L3, R2, L2, R1, L1, SQUARE, TRIANGLE, CIRCLE, X, R3, L3, R2, L2, R1, L1, SQUARE, TRIANGLE, CIRCLE, X quickly at the title screen with the 1P controller.

Misc. Unlockables:
Aya - Finish Stage 1 of 2-Sister Story
Aya Costume 2 - Clear 4 Quests
Aya Costume 3 - Clear 10 Quests
Aya Costume 4 - Clear all Blood Gates/Fill ??? Bar
Aya Costume 5 - Clear 2-Sister Story in BERSERK mode
Aya Costume 6 - Clear Futaba Story in EASY
Eva - Finish 2-Sister Story in HARD mode
Eva Costume 2 - Finish Futaba Story in VIOLENT
Kiku and Hana - Complete all Quests
Makoto - Finish Stage 1 of Futaba Story
Reiko Costume 2 - Clear 6 Quests
Riho and Makoto Costume 2 F- inish Futaba Story in BERSERK
Saki - Finish Stage 1 of 2-Sister Story
Saki Costume 2 - Clear 6 Quests
Saki Costume 3 - Complete All Quests
Saki Costume 4 - Finish 2-Sister Story in BERSERK mode
Saki Costume 5 - Finish 2-Sister Story in NORMAL mode
Saki Costume 6 - Press START button when choosing Saki
Wallpaper 1 - Clear 1 Quest
Wallpaper 2 - Clear 2 Quests
Wallpaper 3 - Finish 2-Sister Story in VIOLENT mode