At the title screen, press Up(2), Down(2), Left, Right, Left, Right, B, A to unlock Reina. If you entered the code correctly, you will hear a voice.
Successfully complete 1 On 3 mode on the hard difficulty setting with Elie, Haru, or Musica to unlock an alternate costume and portrait for that character.
Successfully complete all storylines in story mode to unlock 1 On 2 Free mode.
Unlock all bonus characters and successfully complete Free mode with them to unlock 1 On 3 Free mode.