Magika no Kenshi to Shoukan Maou - 5.2.2 — Discarded Fox Diary

A boy from 21st century Earth, met an accident and later was reborn in Naruto’s Ninja World.
He is born in Uchiha Family and becomes the useless brother of Itachi Uchiha and Sasuke Uchiha…. Let’s see how he changed the Naruto world.

- Description from Novelupdates

Sa Bina was on her way to write her SAT when she suddenly finds herself in a strange world. She is sent to be the old emperor’s concubine, but on their wedding night, the emperor gets murdered by no one other than his own son and the heir! To survive, Bina makes a deal with beautiful but deadly Lucretius and her life in this dangerous kingdom begins.

He died on the wedding of the girl he had a crush on, after a long and successful career. After convincing Yama to send him back to the world, he decides to fix the areas in which his life went wrong. Realizing the lack of love and romance in his past life, he sets out to conquer the hearts of various women.

“If it’s a barbarian you want, then it’s a barbarian you’ll get!”

Reclaimed by her noble family after being swapped at birth, Qin Yining is bestowed a hellish family instead. Just as she turns her situation around and gains acceptance, her country is plunged into danger instead.

Shades of gray color the world. No side is completely good, and no side is completely evil. Refusing to be a trophy won by men, Qin Yining carves her own path instead. In this absolutely riveting and spellbinding tale, what does our MC do when an entire dynasty is at stake?