He is Lovestruck in the Revenge - Chapter 310 - Gu Yihuan and Pang Zijin Extra Story 4

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

“I am Yang Jian. By the time you read this, I've already been dead...”A strange parchment, an eye that peeks into the darkness. This is the memoir of a person who survived.

The top student from the Agricultural University, Qiao Mu, was digging in the experimental field when her hoe struck through to the godforsaken Tupo Village.No money, no rice, no tall, rich, and handsome guy, the aunts and the older female cousins pecked at her every day, making her meals less than satisfying with constant bread rolls, leaving her so hungry she felt faint.Luckily, the Heavens took pity and rewarded her with a tall and handsome man, who was enthusiastic and bold. His debut move was to climb straight into bed, sparking rampant gossip in the village: that Qiao girl, the third daughter, is nothing but trouble at such a young age, shamelessly bringing some wild man into her boudoir to fool around – absolutely shameless!Muniang looked to the sky and bellowed, “Alpacas! You think I'm Hello Kitty when I don't show my claws?”Make a fortune, become rich, fight off the scum, raise a husband – life became increasingly lush.

I became the childhood friend of the protagonist in a novel. The childhood friend who died from taking drugs.