Bloodhound's Regression Instinct - Chapter 241

The century long war had just ended and humanity had managed to get their hands on alien technology, sending them years ahead in terms of technological advancement, fulfilling their hope of finding life outside their planet and their desire to dominate these extra-terrestrial existences. The effects of their technological advancement alone wasn’t capable of giving this result.The appearance of mutations which granted supernatural powers among humans was another boon giving them the chance to act out their darkest desires.Their joy took a dark turn when it was revealed that they were nothing more than livestock to the mysterious race, Xillthars, who cultivated them to that level. Like fattening livestock.Shortly before this dark turn of times was a forbidden creature, Kieran who had been born into the lowest levels of a society created by the greed of humans. To him, life had always been hard, but things got worse after the arrival of the Xillthars as he found himself on a trail of shocking discoveries about himself and the world around him.

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

Kurogami Ichiro was desperate because he couldn’t achieve what he wanted when he once started his martial arts path at age of 8!

Davi was born into a prestigious family of powerful explorers, yet he did not inherit his father’s legendary class.Because of this, he was scorned throughout his childhood. Still, through relentless determination and the support of his best friend, he managed to save enough money to leave his hometown and enroll in the Explorer Academy.Then fate dealt him an unexpected hand, and he received the bizarre class [Harem King] and began his journey to become the greatest explorer of all time.What to expect of the story:- A lot of tension and life-or-death battles- The protagonist’s growth through hard work- And, of course, a harem.