Yu Youyou, a renowned medical professor from a post-apocalyptic world, reincarnates into the body of a thirteen-year-old half-demon girl in a cultivation novel. The original owner was the discarded daughter of Yu Bumie, a powerful sword cultivator and the novel's protagonist, and a demon princess whom he murdered. Abandoned in Tonghua County and raised by a neglectful caretaker, the half-demon suffered from monthly bloodline backlashes that caused agonizing pain and eventual death. Upon waking in her new body, Yu Youyou finds herself with no money, no food, and only a dilapidated courtyard. Her immediate priority is surviving the upcoming backlash, which requires medicinal herbs she cannot afford. Discriminated against by both humans, who view her as demon scum, and demons, who despise her impure blood, she struggles to procure basic painkillers on West Street.
Her fortunes change when she encounters Qi Nanfeng, a wealthy but incompetent young man attempting to refine pills on the street. After his attempt fails spectacularly, producing only charred and useless remnants, Yu Youyou buys a discarded, half-burnt pill for thirty copper coins. She recognizes that the incomplete refinement process preserved the Drunken Heart Flower, a key ingredient for pain relief. Using her advanced medical knowledge, she extracts the herb and creates effective painkillers. Qi Nanfeng, plagued by guilt over his failed attempt, follows her home to ensure she does not die from poisoning. This interaction marks the beginning of an unlikely friendship, as Qi Nanfeng reveals he is preparing for the entrance examination of the Pill Cauldron Sect, the premier alchemy sect in the region.
Realizing that the sect’s resources are her best chance for survival and that she has a genuine interest in alchemy, Yu Youyou decides to take the entrance exam. She travels to the sect’s mountain gate, where she reunites with Qi Nanfeng. During the ascent, her bloodline backlash triggers prematurely due to exhaustion. Qi Nanfeng, mistaking her condition for a fatal injury, frantically calls for help. Their distress is interrupted by the arrival of Jiang Yuan, the chief disciple of the Yunhua Sword Sect, who brings Yu Nianrou, Yu Bumie’s favored daughter from his new wife. Jiang Yuan demands priority treatment for Yu Nianrou, who suffers only a minor facial scratch, while dismissing Yu Youyou as a worthless mortal. Qu Qingmiao, a senior disciple of the Pill Cauldron Sect, intervenes, asserting that all life is equal within her sect and prioritizing Yu Youyou’s life-saving treatment.
The entrance examination requires candidates to identify ten medicinal ingredients in a sealed chamber within seven days. While most candidates struggle, Yu Youyou, driven by hunger and her extensive knowledge of extinct herbs from her past life, meticulously analyzes the ingredients. She discovers rare herbs like Solitary Leaf Flower and Silver Traced Grass, which she secretly consumes to strengthen her body, explaining her improved health upon exiting. On the final day, just as the examination bell is about to toll, Yu Youyou emerges from her chamber. She reveals that the pill formula actually contains eleven ingredients, with the eleventh being licorice added by Qu Qingmiao to mask the bitterness. This insight earns her first place, surpassing Su Yizhi, a talented but less observant competitor. The victory secures her a place in the sect, offering her a path to cure her bloodline backlash and escape the poverty that defined her previous existence.
