In a fantasy world overrun by monsters, the Kingdom of Coffe maintains a front-line base where its sole priestess, Monica, has spent years healing wounded soldiers with her extraordinary restorative powers. Monica is serious, hardworking, and genuinely committed to saving lives. Her powers, however, come with a severe drawback: anyone she heals becomes intensely aroused, and if no specific target is treated, she herself falls into that state. When her exceptional abilities earn her an engagement to the crown prince, a spiteful knight deliberately exposes the side effect to the court. The prince is furious, publicly denouncing her as an indecent priestess and immediately breaking off the engagement. The scandal spreads across the kingdom, and Monica is stripped of her rank and reduced to a commoner. She tries to return to the front-line base, only to find that the base itself is about to be disbanded, leaving her completely without a place in the world.

At her lowest point, a former comrade from the front lines approaches her. Richard, a mercenary from the neighboring Berctorious Empire, asks for her help with a delicate matter: his older brother and sister-in-law are struggling with infertility and need a priestess's assistance. He proposes that Monica come to the empire with him. She hesitates but eventually agrees, seeing no other future left for herself in Coffe. What Monica does not realize is that Richard is not a simple mercenary. He is the imperial younger brother, a prince of the empire, and he has harbored deep feelings for her for some time. His offer is both a sincere desire to help his family and a carefully laid plan to bring Monica into his world.

Once Monica arrives in the empire, she is introduced to Richard's brother, the emperor, and his wife. Her duties quickly expand beyond infertility treatment to include monster subjugation and humanitarian aid. She must handle her powers with extreme care to avoid the arousal side effect, which causes her considerable personal distress and self-consciousness. Richard, now openly protective and affectionate, works to improve the status and recognition of priestesses throughout the empire. His devotion to Monica is intense, and he watches over her constantly, though his political ambitions and genuine love sometimes pull him in different directions. Meanwhile, Monica begins to develop feelings for him, even as she worries about the gap between their social standings.

The narrative unfolds across several major arcs. The first arc centers on Monica's public humiliation and the collapse of her life in Coffe, establishing the injustice she has endured and the stigma attached to her power. The second arc follows her journey to the empire, her gradual discovery of Richard's true identity, and her initial struggles to adapt to a new court and a new role. As she settles in, a third arc introduces the political dimension: Richard's original goal was to elevate the position of priestesses within Coffe itself, but his plans attract opposition from factions that despise the very idea of a priestess wielding such influence. These anti-priestess elements begin plotting against Monica, and the conflict escalates into assassination attempts and open hostility.

A fourth arc shifts the focus back to Coffe, where a catastrophic event threatens the kingdom. Richard receives word that Monica's homeland is burning, and he proposes a drastic course of action: return to Coffe and effectively absorb the kingdom into the empire. The story thus expands from a personal romance into a national crisis, with Monica's unique abilities becoming central to resolving the disaster. Throughout these events, the side effect of her power is not merely a source of embarrassment but a recurring narrative device that forces her to confront her own desires, her self-control, and the way others perceive her. Richard's obsessive love and Monica's earnest determination drive the relationship forward, even as external threats and internal doubts test their bond.

The setting alternates between the monster-plagued wilderness, the militarized front-line base, the opulent but politically treacherous imperial palace, and the beleaguered kingdom of Coffe. The time-limited nature of Monica's powers is also emphasized: her abilities are known to diminish or vanish entirely around the age of thirty, adding a quiet urgency to her mission and her relationship. The story weaves together themes of finding one's true home after being cast out, the struggle for dignity in the face of a humiliating label, and the slow growth of trust and love between two people who each hide parts of themselves from the world.