Disguised as a Man and Exposed, the Prince Craves Kisses

Shen Yue, a 21-year-old struggling web novelist and mercenary, dies of rage after discovering her earnings were only 0.5 yuan. She transmigrates into the body of a 17-year-old cross-dressing shadow guard named Shen Yue, who works for Prince Cheng while secretly being an assassin for the Netherworld Hall. The original owner died from overeating on her first day in the prince's residence. Shen Yue decides to resume her writing career, producing erotic novels that sell well to scholars, while maintaining her cover as a shadow guard.

Her double life is complicated by a poison called Shi Gu San, administered by the Netherworld Hall to control its members. Shen Yue has only three months before the poison activates, and she needs to find an antidote. She kills Agent Six, who was pressuring her to complete a mission, and takes his antidote pills. During a Netherworld Hall assassination attempt on the prince's residence, Shen Yue eliminates the attackers using her triangular blade, catching the attention of Prince Xiao Yuheng. He promotes her to Second Division Director after the previous director, Qiao Er, dies in the conflict.

Xiao Yuheng, known for his handsomeness and stinginess, confiscates Shen Yue's triangular blade as collateral after she eats one of his peach blossom cakes without permission. He orders her to assassinate Song Xianzhi, a marquis heir who discovered Xiao Yuheng's secret and is blackmailing him for five thousand taels. Shen Yue disguises herself and her subordinates Zhang Dayong and Bai Yunfei as women to infiltrate a brothel where Song Xianzhi is staying. The mission involves using an aphrodisiac called Three Days of Spring to kill Song Xianzhi through overindulgence, while recovering the blackmail money. Throughout these events, Shen Yue navigates the dangerous politics of the shadow guard bureau, the Netherworld Hall, and her complicated relationship with the calculating prince.