I think the Macbeth reference is one of the most cultured I've encountered in all my years reading manga with silly credit pages, so congrats once again orchesc/a/ns.
So Saiwa-sama is somewhere between Satanichia and Vignette (from Gabriel DropOut, not that I think most Jahy-sama readers don't already read both) on the "nice demon girl" scale? Maybe on the same level of "evil" as Kurona (not yet seen in the Gabriel DropOut anime)?
@someunregpunk It's not the demon king, since the demon king was stopping it from trying to get to the magical girl. They are probably twins, good and evil version of each other.