The story begins with the protagonist's reincarnation as a baby girl, named Lilia, into a noble family. She retains her adult memories and consciousness from her past life, where she lived a happy life with her family. Her birth is marked by tragedy, as her mother, Claire, dies immediately after childbirth. Her father, the Marquis, is cold and resentful, blaming Lilia for Claire's death and neglecting her. Lilia is raised by a kind wet nurse named Martha and other servants, but her father and older brother, Luke, remain distant.
Lilia, despite her infant body, is determined to live a fulfilling life. She diligently practices her motor skills, crying and moving her limbs to develop her body. She learns to communicate through babbling and develops a strong bond with Martha, who provides her with much-needed affection. She also learns about her family situation: her mother was Claire, her father is the Marquis, and she has an older brother named Luke who attends an academy.
As Lilia grows, she begins to interact more with her family. Her father, Dean, the Marquis, starts visiting her room at night, initially awkward and distant but gradually showing more care. He brings her books and spends time with her, a stark contrast to his initial neglect. Luke, her older brother, also becomes a constant presence, spending his summer holidays in her room, reading to her, and playing with her. He is fiercely protective of Lilia, and their bond deepens. Lilia learns that her family, the House of Alliance, is one of the four ducal houses responsible for maintaining the country's barrier, which protects against "Void Creatures." She discovers she possesses significant magical power, as does Luke and her father, which is crucial for this duty.
A pivotal moment occurs when Lilia, at a young age, accidentally infuses a magic stone with her power, demonstrating an unusually strong magical aptitude. This event, along with her striking resemblance to her mother, draws the attention of her father and the butler, Sebas. Sebas warns that using magic stones is dangerous for children and that Lilia must wait until she is ten to begin formal training. Her father, Dean, initially distant, becomes more involved in her life, spending time with her and Luke.
The narrative also introduces the world's political landscape and the threat of Void Creatures, beings without physical form that drain the life force of other creatures. The barrier, maintained by individuals with strong magical power like Lilia's family, is essential for human survival. The story hints at a complex history involving the first wife of Dean, who divorced him, and Stan, Luke's friend from the academy, who is searching for his father's illegitimate child with a specific eye color.
As Lilia approaches her first birthday, her family life transforms. Dean becomes a more present father, spending evenings with Lilia and Luke. Luke, now a young boy, is devoted to his sister. Lilia's resemblance to her mother and her growing magical potential make her a valuable asset to the family, but also a target. Due to her exceptional magic and the potential for political maneuvering, her first birthday celebration is deliberately kept private, a decision made by Dean and Sebas to protect her. The story concludes with Lilia, now a toddler, surrounded by her loving family, hinting at a future where her magical abilities will play a significant role in the kingdom's protection.
