The Greatest Warrior of All Time Returns - Chapter 105

Embarking on a journey through a mysterious realm filled with boundless dangers and boundless opportunities, Qin Ze, an ordinary soul, is imbued with an extraordinary system that promises unparalleled power and growth. With each challenge overcome, be it fierce battles against demonic beasts or treacherous schemes woven by cunning foes, Qin Ze's strength soars to new heights. This is a tale of relentless progression, where the protagonist's will to survive and thrive fuels his relentless pursuit of becoming the strongest entity in existence. As Qin Ze delves deeper into the secrets of this vast universe, he uncovers ancient legacies, forms powerful alliances, and faces off against the titans that once ruled the land. But amidst the chaos and bloodshed, he never forgets his roots and the promise he made to protect those he cares about. “Unrivaled Ascension” is a thrilling adventure of self-discovery, boundless potential, and the ultimate triumph of perseverance over adversity.

A good-for-nothing man married a beautiful girl but was kicked off the bed on the wedding night. Furiously, he wrote a bill of divorce and ran away.
He was schemed a car accident in which he nearly lost his life. However, it turned out to be a blessing. He swallowed the soul that passed through the outer world, thus obtained superb medical skills and martial arts.
Later on, with the silver needles and invincible martial arts, he embarked on the road of counterattacks and was committed to his great dreams.

- Description from Novelupdates

In the not-so-distant future, a group of Earthlings find themselves mysteriously transported to the Nexus Realm, a fantastical world besieged by monstrous creatures.With no way out of the craziness, they reluctantly joined forces with the realm's inhabitants to combat the constant threat of these otherworldly beasts.To defend the Nexus or Nexaria, powers were bestowed upon them with the promise of returning home after successfully repelling the monsters dangling before them like a carrot.Years passed, and the initial camaraderie between the heroes slowly began to crumble. Still, the Protagonist, Adrian Fenrir, with his power known as Analysis, played a crucial role in understanding the monsters' patterns and weaknesses. However, as the group became more adept at handling the threats, they grew increasingly independent and, perhaps, arrogant.One day, due to a series of mishaps, Adrian found himself surrounded by assassins. He tried his best to drive them off but failed and met a bitter end. It didn't take long for the assassins to do their work, and as per the contractor's request, they decided to dispose of Adrian's corpse by selling it to a mad scientist known for his experiments with creatures from the Nexaria.In need of a fresh subject for his latest project, the scientist transformed Adrian into a chimaera, a fusion of humans and monsters to be sold as a weapon for war.However, the scientist's plan backfired when Adrian, against all odds, regained consciousness within his chimaera body. Fueled by rage and the memories of his betrayal, Adrian seized control over his new body. Now reborn as a chimaera with the ability to absorb organs and gain the powers of other creatures, Adrian vows vengeance upon the mysterious contractor who sent the assassins for him.Once a battleground against monsters, the Nexaria now witnessed a different kind of conflict—one driven by betrayal, revenge, and the extraordinary powers of a vengeful chimaera.

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.