Rosette and Chrono's bond breaks you before you realize what the show is actually building toward. The 1920s setting isn't window dressing, it grounds every supernatural fight, every desperate choice, every moment of tenderness in a world that feels lived-in and real. This is a character study wearing an action anime's clothes, and by the time you understand what loving someone costs in this story, it's already too late to look away.

New York, 1928. The prosperity that followed the Great War has brought something darker with it: demonic Sinners are spreading across America. The Magdalene Order exists to counter them, and its New York branch is home to two exorcists who seem out of place there: Sister Rosette Christopher, young and reckless, and her partner Chrono. They are a famous team, very good at destroying demons and just as good at wrecking everything around them. Both are driven by dark pasts. Rosette hunts demons in the hope of finding her lost brother Joshua, who was taken by the demon Aion, and Chrono shares a bloody history with Aion too. As the demonic threat grows more dangerous, the pair must fight it off, trace where it comes from and keep searching for the truth behind Joshua's disappearance. The story mixes supernatural action with romance, and it leaves their relationships, secrets and fates to come out over time.