According to Chinu, the Miko was never born from any of the previous generations of Twin Stars.
The Miko is only mentioned throughout the series and is the prophesied child of a pair of Twin Star Exorcists. The sex of Miko, and which child of the Twin Star couple Miko is, are currently unknown, although Miko is usually assumpted as a girl.
Powers and Abilities
Extreme Enchanted Powers - As the one whose destiny is to end the war, the Miko is speculated to be extremely powerful.