I'm an Ordinary Returning Student at the Academy - Chapter 195

The Third Miss of the Qin Clan is a useless and timid person. When the Prince withdraws from her marriage, she commits suicide by jumping into the river. In the 21st century, Qin Chu, a genius agent, is framed and his soul crosses over to the Third Miss of the Qin Clan. So what if she’s useless,

With the Goddess’ blessing, he became a 『Divine Knight』 and founded an Empire.
As time passed, he grows older, and by the time the heavens called for him to come, the Goddess showed before him, asking for his last wish.

He wished to be reincarnated in the future.
He dedicated all his life for his people, he had no time to master his own arts.
This time, he wishes to live for himself, forging his body to the utmost limit.

The Goddess complied with his wish.
In the far future, the King shall reincarnate as the 『daughter』 of a renowned Knight family.
And, under some circumstances, she is labeled as a failure of a Knight, however——

「How convenient. I can stand on the foremost line without needing any rank. No better training than actual combat!」

Thus, the legend of the world’s strongest, most beautiful Knight Disciple (♀) has begun—

An ordinary student, a wretched peeper, a cowardly teenager with a kind heart. In a terrorist attack, he inherited the knowledge of countless elites, embarked on a path of God Jagged Tu…

He is an artist!

He is a mathematician!

He is a psychology Doctor!

He is a master of fighting!

In fact, he is a man

Taken off raw site:

A wretched, dirty young man is working during the summer when he was caught up in a mysterious explosion. After that explosion, the young man is then left with the memories and knowledge of dozens of the world’s experts.

He has changed, his heart has become cold, iron-blooded. He became a killing machine, his mind turned mechanical, calculative. Everything goes according to his plans and calculations!

In this magical, slaughterous world, a door is opened for him…

- Description from Novelupdates

An ultimate warrior, the one and only Alchemy Emperor, Ling Han, died in his quest to achieve godhood. Ten thousands years later, he, with the ‘Invincible Heaven Scroll’, was reborn in the body of a young man with the same name. From then on, winds and clouds moved as he set himself against the uncountable geniuses of this new era. His path of becoming a legend has begun once more. Of all eras underneath the heavens, I am the strongest!

- Description from Novelupdates