Yui, a reincarnated individual with memories of her past life as Tsumugi, finds her calling in sewing. Born into the Nuille family, known for their ability to sew blessings into clothes using special spider silk, Yui discovers she can see spirits and manipulate magic as an infant. She secretly mends spirits' tattered "clothes" (which are part of their bodies and power), making them sparkle. Despite her exceptional sewing speed and beauty, her family deems her worthless because she doesn't use their specific magic-infused spider silk, favoring her younger sister who, though messy, can infuse magic. Yui endures years of abuse, neglect, and poor living conditions, surviving only due to the spirits' subtle healing influence on her food and injuries.
At fifteen, Yui is cast out and sent as a seamstress to the Calostira Rodan household. Lord Rodan, his head butler Ullde, and the staff quickly recognize her severe malnutrition and abuse, welcoming her with kindness, a private room, proper food, and new clothes. This stark contrast to her past fills Yui with relief and gratitude. Using her first salary, Yui buys fabric and creates scented pouches for the household, secretly infusing them with powerful blessings using her magic and spider silk. This act attracts numerous spirits, amplifying the blessings to a level comparable to the Nuille family's founder.
Ullde and Rodan discover the extraordinary power of these pouches, noting the presence of rare spirit-infused herbs and the founder-level blessing sewing. They realize Yui's true abilities and the potential danger if her abusive birth family were to learn of them. Soon after, Scull, Ullde's husband and Rodan's head butler with "magic eyes" (the ability to see spirits), arrives. He reveals the mansion is now heavily protected by spirits due to Yui's presence and asks her to "treat" injured spirits he has protected. Yui realizes her mending is actually healing, preventing spirits from losing power and disappearing. She also discovers her spider's silk uniquely fixes magic, preventing it from dissipating like others'. Scull, recognizing her unique power, formally requests her continued help, while Aunt Line warns Yui that her "magic eyes" make her a potential royal concubine candidate, and her birth family might try to reclaim her. Rodan promises to protect her.
A month-long, painful growth spurt, followed by two months of rehabilitation, dramatically transforms Yui's appearance. Her hair turns shining silver, her skin becomes flawless, and her body develops delicate curves, making her an ethereal beauty compared to a legendary royal princess. This new beauty, however, is deemed a "criminal magnet," leading to a ban on her solo outings. Meanwhile, the current Nuille family head, enraged by Rodan's rising status and Yui's departure, plots to use a family curse to sever Yui's spider contract, believing it will harm Rodan and his allies.
Yui, now fully recovered, demonstrates her exceptional skill by creating intricate lace with her spider's silk. She expresses a desire to make wedding dresses, reflecting on her own parents' dysfunctional marriage and the maids' similar struggles with relationships. Her resolve to use her skills for good is tested when Rodan introduces her to the former King, Romestometoro Ajit. Appalled by the former King's ill-fitting, poorly sewn (though blessing-infused) clothes, Yui, with the help of her male spirit companion who cuts the blessing-infused fabric, decides to openly use her full, founder-level sewing abilities to create comfortable, well-made clothes for him, driven by a mix of trust in Rodan and anger at the poor craftsmanship. The former King is astonished by the comfort of her initial shirt, highlighting the stark difference from his previous attire.