MTL - I Want To Be Qin II - Chapter 13 The origins of Aiyu all started from Marquis Wenxin.

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.

Chen Sha came to a world of immortal martial arts and was ordered to take charge of the world’s first sect.

Before his death, the previous chief told him:

“If you don’t become the best in the world for one day, you are not allowed to go down the mountain for one day.”

So he closed himself in painstakingly, crossed the heaven gate in his body, and faced off against the ancient and modern powerhouses…

…

Many years later, Chen Sha recalled the day he went down the mountain,

From the moment he descended the mountain, he was number one in the world.

In the next ten epochs, any gods and demons have returned, immortals and Buddhas have lived in the world, ancient powers and ancient gods have appeared one after another.

No matter how the times change, he has always been No. 1 in the world and has never changed.

- Description from novelbuddy

A man was transported to Ancient China and eventually became a servant of a declining household without a male heir. He utilized his wits and modern knowledge to help the household and eventually become trapped in the sea of political turmoils of the period.

- Description from Novelupdates

The Principality of Atall lies between two great powers: the Kingdom of Allion to the west, and the Holy Dytiann Alliance to the east. Leo Attiel, the second-born prince, was sent to Allion as little more than a hostage, where he studied and trained in the military arts under a frontier general. And now, the times have reached a turning point.

Relations between Allion and Conscon Temple, a neutral land adjoining Atall, have worsened. Percy, sent from Atall as reinforcement; Camus, a warrior monk; and Kuon, a mercenary from a remote region, join forces to resist the looming threat of Allion’s army.

At the centre of the fighting, the three of them and Leo are about to have their fated encounter.