You can customize the game by hitting Yellow (once or twice), Red (one to four times), Blue once, in order. The number of times that Yellow and Red are hit changes various aspects of the game, allowing you to create any desired combination.

Yellow once: CG intermission sequences
Yellow two times: Animated intermission sequences
Red once: Japanese text and voices
Red two times: English text and voices
Red three times: Japanese text with English voices
Red four times: English text with Japanese voices

Select the "Cheats" option at the main menu. and enter:

[Yellow]x2, [Red]x2, [Blue] - English language PC version game
[Yellow]x2, [Red]x4, [Blue] - Japanese language PC version game
[Yellow], [Red]x4, [Blue] - Japanese language PS2 version game
[Red]x5, [Blue]x3, [Yellow], [Red], [Blue]x2, [Yellow]x3 - Olha demo
[Red]x4, [Blue]x4, [Yellow]x4, [Blue]x2, [Yellow]x2, [Red]x2 - Unlock game completion bonuses