Sasha Rebecca, the second daughter of Earl Rebecca, is born into a prestigious family of alchemists but is shunned and neglected as the child of a concubine. Despite having genuine talent in alchemy, her older sister consistently takes credit for her work, leaving Sasha branded a failure. On her fifteenth birthday, her father disowns her, throwing her out with nothing. With nowhere to go, she is unexpectedly scouted by Nagare, the prince of the neighboring kingdom of Astraea, who invites her to become the country’s state alchemist.

Upon arriving in Astraea, Sasha finds the kingdom in crisis: a monster stampede has caused a severe shortage of healing potions, and the situation is dire. Traditional methods of gathering materials are failing, but Sasha, drawing on her unorthodox creativity and deep knowledge of alchemy, proposes a radical solution that turns the shortage around. Her success earns her a place among the royal alchemists, and she begins to build a new life far from the family that rejected her.

The story follows Sasha as she tackles a series of escalating challenges. She develops a cure for the mysterious Minato disease and later discovers that counterfeit potions are circulating in the capital, affecting even Queen Ran, Nagare’s mother. Investigating the source leads her to uncover a plot threatening the royal family. In another arc, a sweet shortage linked to depleted magic crystals draws her and Nagare to the tower city of Ve Zaria, where they must solve a ghost disturbance in the labyrinthine dungeon tower alongside the eccentric magic-crystal expert Yumis. Throughout these adventures, Sasha’s low self‑esteem slowly gives way as her brilliance is recognized, and she forms genuine bonds with the people of Astraea, especially the kind‑hearted Prince Nagare. The series balances light‑hearted moments—often revolving around Sasha’s love of sweets—with the kingdom‑saving stakes of her alchemical innovations.