The provided chapters detail the life of Spica, an adopted daughter of the Earl of Emmental, and the dynamics within her adoptive family. The narrative begins with Spica, at 18 years old, writing a heartfelt letter to her adoptive parents and three older brothers, expressing her gratitude for their care and love. She announces her intention to repay their kindness by taking on the role of a "Barrier Maiden," a duty she believes will aid her adoptive father, the Earl, and her eldest brother, Cain, who is the heir. She also mentions designing dresses and jewelry for her adoptive mother, Violet, and preparing a special tea blend. To her second brother, Alex, who suffers from Monaza disease, she offers her "magic eyes," and to her third brother, Flet, who always praised her work, she gives a sword tassel and her sacred stone. Finally, she apologizes to her adoptive sister, Stella, for returning what was not truly hers, implying Stella is the Earl's biological daughter.
The story then flashes back to Spica's childhood. She was adopted as an infant around the same time the Earl and Countess had their biological daughter, Stella, who was subsequently kidnapped. Spica's mother was Violet's former personal maid and confidante, and Spica's own innate holy power and resemblance to Stella made her adoption a swift decision. Spica grew up believing the Emmental family to be her true family. Her adoptive father, Masky, is a middle-aged politician. Her adoptive mother, Violet, is a beautiful noblewoman. Cain, the eldest brother, is a genius in magic. Alex, the second brother, is afflicted with Monaza disease, which gradually steals his sight and holy power, but he possesses great talent in music. Flet, the third brother, is skilled in swordsmanship and aspires to be a knight.
The chapters depict the affectionate and somewhat chaotic daily life of the Emmental siblings, all of whom dote on Spica. Flet often bursts into Spica's room, eager for outings, but is usually thwarted by Alex, who has opera plans with Spica. Spica, though young, displays a mature and somewhat prim demeanor, often chiding her brothers for their lack of manners. Alex's Monaza disease is explained as a serious condition requiring the transplantation of a "holy origin" or "holy mark" for a cure, highlighting the rarity of donors and the societal implications of lacking holy power. Flet, despite his initial frustration, readily concedes to Spica's requests, especially when Alex's health is involved. Cain, the eldest, also visits, showering Spica with expensive gifts, much to the playful chagrin of his younger brothers. The brothers' rivalry over Spica's affection is a recurring theme, often manifesting in gift-giving and attempts to outdo each other in pleasing her. They fiercely protect her, having once physically and magically retaliated against a noble who insulted her.
The narrative then shifts to the perspective of Cain, who recounts the birth of his younger sister, Stella, and her subsequent kidnapping. The family's grief plunged their home into a somber atmosphere. Cain found solace and purpose in magic, becoming a prodigy. He describes the moment he first met Spica, a beautiful infant who immediately grasped his finger, solidifying his resolve to protect her. He details how Spica became the center of their lives, their days filled with joy and her adorable antics. He also touches upon the societal structure of their world, where holy power is crucial for noble status and the existence of "Barrier Maidens" who sacrifice themselves to protect the nation. Cain's research into this magic is a significant part of his life.
Alex's perspective reveals his initial coldness and detachment as a child, feeling like a spare heir. He describes his feigned comfort to his parents after Stella's disappearance, masking his true feelings. Spica's arrival transformed him; her innocence and gentle nature captivated him. He recounts how he overcame his fear of touching her and began singing lullabies, discovering her love for music. His talent flourished, and he became her primary caregiver for lullabies until Spica declared she no longer needed them. He then reveals his diagnosis of Monaza disease, triggered by Spica noticing "sparkles" around his eyes, which he initially dismissed as tears. His early detection, thanks to a skilled doctor and Spica's observation, is presented as a stroke of luck, allowing for potential treatment. He chooses to pursue music, staying closer to Spica, who becomes his muse.
Flet's narrative highlights his straightforward nature and his transformation from a rambunctious child into a protective knight figure for Spica. He explains his initial rough behavior and how Spica's existence inspired him to become a knight to protect her. He dedicates himself to swordsmanship, surpassing his brothers, and cherishes Spica's gifts and her affection. He views himself as Spica's primary protector, contrasting himself with his brothers.
The chapters also delve into the past of the Earl and Countess. Violet, the Countess, expresses her desire for a daughter, having had three sons. She recounts the joy of Stella's birth and the subsequent devastation of her kidnapping. She describes the prolonged period of grief and the efforts to find her daughter. The narrative then introduces the story of Rizan, Violet's former maid and confidante, who also becomes pregnant. Rizan's husband, Mr. Faker, a semi-baronet, is introduced. After Stella's disappearance and Rizan's difficult childbirth and subsequent death, Mr. Faker is left to care for his infant daughter. Violet, deeply moved by the resemblance of Mr. Faker's daughter to her own lost child, decides to adopt her, naming her Spica. This adoption brings renewed joy and purpose to the Emmental family.
Finally, Spica's own reflections reveal her awareness of her privileged upbringing and the lessons she has learned from her family about kindness, gratitude, and the responsibilities of nobility. She internalizes the concept of "noblesse oblige" and vows to live a life of integrity, compassion, and honor, cherishing her family and her role within their society.
