Unlock Lean:
First, use Kou or volt to infiltrate the mikado building.
Next,use Kou to beat Kaldea on the space ship.Then, use kou
to fight Duragon. After the "Final" scene at the bar, Kou will
get a phone call telling him to go to central sqaure. There,
you will have to beat Kou's old partner, Lean. If you beat her,
you will unlock her in versus and survival mode.