In the aftermath of the demon lord's defeat, the world remains unstable. Sister Alicia Snowell serves the Holy Church as both a devoted bride of the gods in public and a top inquisitor who eliminates threats in secret. She receives an impossible assassination order to kill Elcyon, the hero who slew the demon lord. The hero’s divine protection makes direct attack futile, leaving only one method to succeed: to win the hero’s heart and then strike. When Alicia finally approaches her target, she discovers Elcyon is actually a girl named Cion, forcing the inquisitor to navigate the awkward task of seducing another young woman while questioning her mission.

Alicia is a cynical and bitter operative whose faith in the Church and its doctrines has been worn down by the dark tasks she performs. Despite her hardened worldview, she wrestles with a genuine desire to protect people. Across from her stands Cion, the heroic slayer of the demon lord whose growing fame has made her a political target for the Church. As they confront remnants of the demon army still terrorizing the land, the nature of their relationship shifts from deception to something more genuine. The pair travels together negotiating with demon leaders and facing supernatural threats, including a massive wolf-like figure who reminds Cion of a missing mentor and the kidnapping of a saint that raises the stakes even further.

The conflict deepens with the emergence of a former slave who attempted to destroy the world a decade ago and has now returned. This villain excels at psychological manipulation, forcing both heroines to confront their deepest fears and doubts. During a heated battle, Cion admits she loves Alicia without fully realizing the weight of her words, only to have the villain twist the moment by suggesting Alicia might actually be an assassin sent to eliminate her. The truth proves even more complicated, as Alicia survives death twice, undergoes a blood transfusion that gives her animal ears and a tail, and eventually learns she is the daughter of the demon lord that Cion once killed.

The story builds toward major revelations as the two heroines fight side against side against a villain determined to exploit every secret and weakness. Alicia must reconcile her intense cynicism about religion and the world with the kind heart that still wishes to save everyone, even those who have already committed mass murder. The narrative follows their journey through political intrigue, supernatural battles, and emotional turmoil, all while a former mentor and beloved cat disappear under mysterious circumstances. Through assassination plots turned into something far more personal, the series explores whether a relationship forged in deception can survive the weight of truth.