As daughter of the former demon lord, Mio's foster parents were slain by powerful demons after her life. Still seeking to slay her, Basara reveals himself as a member of the hero clan--an enemy of the demons--and vows to protect Mio as a member of his family.
After all, we're your little sisters.
Immerhin sind wir deine kleinen Schwestern.
Después de todo, somos tus hermanas.
Después de todo, somos tus hermanas.
Après tout,
Dopotutto, siamo le tue sorelline.
Afinal de contas, nós somos
 suas irmãs mais novas.
Мы ведь твои сестрёнки как-никак!