The Legend of Chu Qiao: Division 11's Princess Agent - Chapter 169

A tale of avenging a father’s murder harbored hidden circumstances. A young man rose, a story steeped in bloodshed.

A river song, triggered a legend of the rivers and lakes.
Tian Zun’s life motto: “My sword is the truth.”
Shen Lang’s life motto: “To serve people with morality, those who are dissatisfied are dead.”

- Description from uukanshu (translated)

MC (female protagonist) dies in a plane crash and wakes up in the body of a beautiful but corrupt and lascivious prime minister in ancient times, Zhang Qinglian. As circumstances decree, he (she) cannot reveal that the original owner’s soul is gone else calamity might occur. So he (she) decides to walk a righteous path, determined to help the lovely but simple little emperor rule the country. Not backing down after facing torture, not losing courage, destroying rebellions and facing off with scheming princes.

- Description from Novelupdates

Zhuo Yifan was the Demon Emperor. One day, he managed to lay his hands on an ancient emperor’s book, the Nine Serenities Secret Records. As the book was coveted by many, he was targeted by experts and was even betrayed by his student.