Mio is a resident of a secret Ganin village of the Kagerō Clan.
Mio lived in a secret village with her husband, father and child. During the attack of the enemy Ganin on the settlement, Mio tried to escape from the house with the child, but her elderly father stopped her and ordered her to bring the katana. It was then that a winged ganin flew into their house and blew itself up. Thus, the entire Mio family died. Thus, the entire Ryūgen settlement was destroyed.