Hold D while entering the options menu to access hidden options that allow changes to the speed, recovery type from attacks, and more.
Fight against G-Akiha:
Highlight the “Arcade Mode” option at the menu, then hold D and press A to select it. The character selection screen background will turn blue to confirm correct code entry. The best times that G-Akiha has been defeated will also be posted on a screen.
Fight against Aozaki Aoko:
Successfully complete Arcade mode without losing any fights to fight Aozaki Aoko after White Len. Win the match to unlock hidden dialogue during the ending credits and an extra image of the character that defeated her.