She was rescued from the burning planet Terra on the Invincible, an airship. From there she lived on Gaia, in the Black Mage Village, learning that she was a person, and had a soul.
Zidane took her to live with himself and Queen Garnet at the Alexandrian Castle, where she is the caretaker of their children, Terra and Leo.
One night when a silver dragon attacks herself and the children, Mikoto is charged with destroying the Iifa Tree, and the Mist once again threatening to devour the world.