MTL - My Chip that Disguises Itself as a Cell - ~ All of a sudden the mood is gone

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

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

Kyoukai Senjou no Horizon chronicles the story of a futuristic civilization returned to Earth after constant warfare hindered them from traveling beyond the post-Apocalyptic Earth. At this stage, a small archipelago called the Divine States were the only hospitable land on Earth. In order to regain the space-faring technology they had lost after many years of war, they decided to recreate history with a book called the Testament as a guide.

It is the year 1648 in the Testament Era. Toori Aoi, Chancellor and Student Council President of the only academy on the airborne city-ship Musashi, faces the ten-year anniversary of the death of his childhood friend Horizon Ariadust in an accident. As he prepares to celebrate the occasion by proposing to P-01s (an automaton who looks exactly like Horizon) he discovers that his suspicion about P-01s’ appearance actually has a basis in truth; P-01s is in fact Horizon Ariadust, reborn into a robotic body. In addition to this, Horizon’s emotions had been stripped away and are now stored in eight powerful weapons called the Mortal Sin Armaments; which are now in the possession of key people in various established countries in the Divine States.

To retrieve the emotions of Horizon Ariadust, Toori Aoi along with his friends and allies begins a crusade against different obstacles as key events in history are recreated in a futuristic manner.

A Di [legitimate-born] daughter of a noble house turns into an abandoned daughter. No father to dote on her, no mother to love her, no problem. She uses one silver needle to save a dying man. What’s so unusual about a medical injection? She roams all over the world with a scalpel in her hand. Cutting throats, cutting open abdomens, cutting open skulls to mend bones. With amazing medical skills and ethics, she gathers a flock of officials, obtains the will of heavens, gains public favor, and receives Taizi’s [Crown Prince] doting. In the midst of a powerful momentum, her cheap father comes to reunite. She coldly refuses to go home or acknowledge ancestors.

“I was abandoned by you over and over again. Now you want to use familial affection to coax me back. You don’t want to recognize this daughter. My heart is cold, I want to leave. Beat it, father!”

- Description from Novelupdates