Working closely with Baatar Jr. and Commander Guan, she was the head of weapons development for the Earth Empire's southern forces during the rule of Kuvira, and participated in an armed holdout following the latter's surrender.
Just before Kuvira's surrender in Republic City, Sheng had developed groundbreaking new brainwashing techniques, using a combination of ancient methods and new technology. However, Kuvira surrendered before the methods could be tested. Guan, the commander of the Earth Empire's southern forces, continued to pursue these techniques and refused to give up the southern Earth Empire following Kuvira's surrender. Sheng wanted to discover ways to brainwash people permanently, ensuring Earth Empire rule for years to come, and Guan conspired with her to restore the Earth Empire to power.
Shortly after Kuvira was sentenced for her crimes, Guan got wind that Prince Wu was planning on turning the monarchy structure of government in the Earth Kingdom into a democratic republic, and told his forces that he would never abandon them as Kuvira had, and that the Earth Empire would rise from defeat and become more powerful than it had ever been. Kuvira was released from prison temporarily so she could give the final order to Commander Guan's troops to surrender, they instead chanted their support to him, showing her that they were no longer loyal to her. Guan claimed that she was never fit to lead the Earth Empire, and that she was weak.
When Kuvira learned that Sheng had previously employed her inhumane brainwashing techniques at the re-education camps, she was disgusted and voiced her disapproval, as she was unaware the lengths that Sheng and Guan were going to enforce her policies. However, Sheng and Guan ignored her objections, claiming that the end result always justified the means and as long as they got results, Kuvira was more than happy to turn a blind eye to their methods. After Sheng used her brainwashing technology on Wu, he moved the date of the election for governor of Gaoling, which Guan won in a landslide. Sheng and Guan then attempted to brainwash Korra's friends to turn against her, as well as trying to brainwash Kuvira herself. After Guan is defeated by Kuvira, Sheng attempted to escape but was ultimately stopped by Asami Sato, who stunned her with an electric glove in revenge for Sheng doing the same to her.
With both Sheng and himself defeated, Guan subsequently ordered his entire army to stand down. As of the dissolution of the Earth Empire's southern forces, the Earth Empire was permanently disbanded and the Earth Kingdom officially became a republic. Sheng's fate is left unknown, but it is likely that she was sentenced to prison for her brainwashing crimes and attempted coup.