Chapters 3-12 of the light novel detail Anastasia's devastating betrayal and subsequent return to the past, setting her on a new path.
Initially, Anastasia, the mage of the hero Shin's party, lies dying after contributing significantly to defeating the Demon Lord. Her body is ravaged by the forbidden magic she used and the curse she absorbed, all for Shin, her lover, who promised to marry her. Instead of gratitude, Shin and Anastasia's younger sister, Jamie, reveal their true intentions. Shin confesses he only used Anastasia as a tool, planning to discard her once her role was fulfilled, and Jamie gloats that she will marry Shin and inherit Anastasia's title. Anastasia dies filled with regret and the realization of her exploitation.
However, Anastasia awakens to find herself back in her younger body, three to four years prior, attending Lapis Magic Academy. Her pain is gone, and her body is healthy. She discovers a diary confirming she is fourteen years old, just starting her academy life, a year and a half before meeting Shin. This past-life knowledge, including lost magic and combat experience, becomes her greatest asset.
Upon returning to the academy, Anastasia's extraordinary display of power during a practical magic exam, where a simple "Ignition" spell causes a massive explosion, shocks her classmates and the teacher. This incident draws unwanted attention, particularly from Reginald, a confident and talented student who initially dismisses Anastasia, and Foil, a physically strong but less refined student who challenges her.
Anastasia's focus shifts to avoiding Shin and the future she experienced. She learns that Shin will be chosen by the holy sword in about a year and a half, and she will be ordered to join his party. To evade this, she decides to run away and pursue her own path. She also resolves to investigate the cause of the increased monster activity that led to the Demon Lord's rampage and the hero's emergence, suspecting a connection to a failed magic experiment by Researcher Foster.
Her path takes an unexpected turn when she discovers a hidden room in the library, where she meets Brant, a third-year student and the academy's top prodigy. Brant, intrigued by Anastasia's ability to bypass the room's powerful concealment, offers to teach her his magic in exchange for her knowledge of ancient magic. This exchange marks the beginning of a unique partnership, as they discover a shared passion for magic and a mutual lack of peers who can understand their level of discussion. They also encounter a mysterious transparent sphere that grants them new magic: Anastasia gains "Teleportation," and Brant gains dangerous demonic spells like "Blood Chain" and "Plague."
Meanwhile, Anastasia's newfound confidence and power attract attention. Reginald, initially dismissive, witnesses Anastasia's transformation and offers her friendship, helping her with her appearance and posture. Foil continues to harass Anastasia, but Brant intervenes, subtly intimidating him and teaching him a lesson about humility. Anastasia also begins to forge a friendship with Reginald, who adopts the nickname "Lena," and they plan to go shopping together. Foil, humbled by Brant's intervention, offers to teach Anastasia about being a hunter as an apology.
The chapters conclude with Anastasia and Lena becoming friends, and Anastasia preparing to become a hunter to earn money and train, while still aiming to prevent the future she knows. Her interactions with Brant and Lena, along with her past-life knowledge, set her on a course to change her destiny and potentially the world.
