After being unexpectedly transported to the Vollachia Empire, Natsuki Subaru finally reunites with the awakened Rem. But their joy is short-lived, as the two become entangled in a massive civil war that engulfs the entire empire. Facing off against Vincent Vollachia, the dethroned emperor, Subaru vows to return to the Kingdom of Lugunica alongside Rem. But upon entering a fortress city, he is ambushed by an unpredictable spiral of deaths and is forced to brutal confront to consequences of his choices.