Olivia Bell Avine, daughter of the respected Marquis Avine and engaged to the Crown Prince, finds her life shattered when she is imprisoned and accused of attempting to poison the Saint. Her stepmother, Isabella, orchestrated this downfall, forcing Olivia to ingest a slow-acting poison that leads to her agonizing death. In her final moments, filled with despair and resentment towards the world and the creator god, Demiurge, Olivia wishes for a life free from suffering and the desire to be loved.
Upon death, Olivia awakens in a warm, ethereal space before Demiurge, the creator god. He reveals that while she did poison the Saint's tea, it was under her stepmother's command, and her soul was summoned from another world, causing her soul to struggle and suffer excessively in this one. Demiurge, feeling pity and a sense of responsibility, offers Olivia a chance to live a happy life and grants her "unique knowledge and power." Olivia's wish is to never die by poison again and to live a peaceful, loved life. Demiurge grants her wish, but with a twist: she is reborn as a thirteen-year-old Olivia, three years before her original death, and gains the "Poison Skill" with "Poison Resistance Lv. 1." This new reality is revealed to be the world of an otome game she played in her past life, where she was the villainess.
Olivia, now possessing her past life's memories and a game-like status screen, is initially dismayed by the "Poison Skill," as it seems to contradict her desire for a peaceful life. She discovers her stepmother has been poisoning her for a long time, and her new skill allows her to identify and resist the poison, though at the cost of experiencing its effects if her skill level is insufficient. She befriends Ann, a timid maid who is being blackmailed by the head maid, and uses her knowledge of detoxification to improve her health. Olivia begins a rigorous detoxification regimen, incorporating yoga and specialized herbal teas, much to Ann's bewilderment and eventual profit.
Her stepmother, Isabella, continues to plot against her, but Olivia's newfound abilities and knowledge allow her to counter these attempts. The head maid is dismissed by the butler, Fred, who is loyal to Olivia and her father, the Marquis. Olivia also receives a vast array of cosmetics and beauty products, a gift from the butler, allowing her to indulge her past life's passion for makeup.
The story progresses to the day of a royal audience, where nobles whose children are of age to enter the Royal Academy are summoned. Olivia, despite her frail appearance, decides to attend, aiming to prevent the assassination of the First Prince, an event that occurred in the original game's timeline and could alter her fate. She uses her makeup skills to present a healthier appearance, surprising her family and the knights.
At the Royal Palace, Olivia encounters the First Prince, Noah Arthur Igburn, who is struck by her resemblance to his deceased mother. While speaking with him, Olivia's status screen reveals that his tea is poisoned with a Level 2 poison, exceeding her current resistance. In a desperate attempt to save him and prove her claim, Olivia drinks the poisoned tea herself. Though she experiences the poison's effects and falls into a temporary state of "suspended animation," her "Poison Skill" activates, preventing her death but not the damage. She is revived by Noah, who is now concerned for her. The experience leaves Olivia frustrated with Demiurge's incomplete powers and the dangerous nature of her new abilities, but also determined to level up her skills to protect herself and potentially alter the game's narrative.
