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.
That's an outright master-servant 
relationship, isn't it?
Das ist eine reine
Meister-Diener-Beziehung, richtig?
Vaya relación entre maestro y siervo...
Vaya relación entre maestro y siervo...
Comme si j’étais
vraiment un vassal…
Quindi in pratica si tratta di una relazione
Servo-Padrone, no?
Isso será uma relação 
Mestre-Servo para valer, não é?
Самые что ни на есть отношения 
господин-слуга получаются.