Executioner and Her Way of Life, Vol. 3 (manga)

The ritual to kill Akari has begun, and everything is going smoothly. Menou believes this will finally be the end of the Otherworlder—until she receives word from Momo about Orwell's betrayal. In the face of the archbishop's intricately woven plan and the arsenal of taboo conjuring tools at her disposal, it seems Menou and the others won't stand a chance. But perhaps the power in Akari is greater than even she herself realizes...