In arcade duel, when you win with a pre-set duelist
on the first level you will unlock a new corresponding color character
under him or her. For example, play as Keroc (first black duelist)
and win all six fights with him. You will then unlock Mintora
or someone to that effect. Win six fights with her and you will
be able to play as Ishan's Shade. By playing as pre-set character
on arcade mode, you will unlock a new character.