From the in-game profile:Edit
"A powerful mystic in her own right, Sheva is an evil woman with evil aspirations. Nothing pleases her more to see people in pain and suffering. Sheva has always been able to enchant men with her beauty, and thus she controls them and bends them to her will.
Drawn to the ambition and hatred within Kang, she married him to create a duo to be reckoned with.
Losing the battle with Tai, she was banished along with her husband and his generals to the tower on Mt Houshin."
Sheva is the boss of stage 4-3 in the game. In battle, she creates many false dopplegangers of herself to confuse the player.