Cynthia Rhuddlan, a viscount’s daughter, suddenly regains memories of her past life as an ordinary Japanese woman. She realizes she has been reincarnated as a villainous noblewoman from a dating sim, and the story’s heroine is currently trying to steal her fiancé, the unremarkable son of an earl. Rather than fight for him, Cynthia is relieved and immediately breaks off the engagement, finding the prospect of a new life far more appealing. She sets her sights on a character she remembers from the game: Siraiya, the third son of a duke. In the original story, Siraiya is a feared yandere villain with a tragic and abusive past; if the heroine helps him, he becomes dangerously attached, potentially leading to a murder-suicide. Cynthia, however, sees him as the perfect match and boldly declares that he is the one she wants to marry.

The story takes place in a noble society where class and political maneuvering are as important as romance. Cynthia is a highly competent protagonist who uses her knowledge of the game’s plot to navigate this world. She quickly learns that the antagonists from the game are not particularly smart or effective, but their cruelty is still damaging. Siraiya is being tormented by his own family, who treat him as a tool. As Cynthia begins to interact with him, she offers him genuine kindness, helps him with his appearance, and provides the emotional support he has never received. In response, Siraiya becomes devoted to her, transforming from a broken man into an almost perfect and doting partner.

A major narrative arc involves Cynthia accidentally using her game knowledge to solve the crown prince’s tragic romantic subplot, earning her powerful allies. Another significant thread is her effort to extricate Siraiya from his abusive family situation, who oppose their relationship. While the villains she faces are often incompetent, their maliciousness still presents real obstacles that Cynthia must outmaneuver using her wits and understanding of noble protocol. Her own family proves to be understanding and supportive, eventually adopting Siraiya as their own. The central conflict is not whether Cynthia will succeed, as she is determined and capable, but rather how her proactive and loving approach will save the yandere villain from his dark fate, leading to a reverse Cinderella story where the villainess’s love redeems the villainous nobleman.