Harry Potter: A Certain Ancient Rune Professor of Hogwarts (TL) - Chapter 14

Leguna. An orphan. His life changed dramatically the day the thieves’ guild happened to select him for training and development. He would go on to become lifelong friends with a loyal mercenary, the partner of a beautiful magus who was cold as ice, the savior of a mysterious disfigured dark-elf girl with a talent for the Breath, and the unlikely caregiver for a feisty young maiden. And yet, who would be with him to the very end?

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates

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.

What is a genius? Capable of comprehending any battle skill regardless of the skill itself and sweeping away the bottlenecks while cultivating a new technique; this is a true genius! He Yiming was originally an ordinary youngster in the He family’s estate with not too extraordinary aptitude in learning martial arts.