HxH: Apex Predator - Chapter 18: Tactics x Traps

Perhaps it is the choice of fate. As a senior otaku, Qian Lingfeng got the “steel shell system”. However, when he swept the world with the system, became a local rich man, made all kinds of beautiful women, opened a harem, and realized the ultimate fantasy of thousands of otaku, he found that things seemed far from simple!
When the end comes, biochemical zombies suddenly come down, fierce beasts are in power, bloodthirsty zerg roam to kill the world, and human lives are comparable to dirt. Where will weak human beings go in this world? Is humanity going to be extinct? Or … can an otaku save the fate of the human race?

- Description from Novelupdates

"Who touched you?" he asked, his eyes brooding down at her and when she didn't answer, his voice thundered in the room, "WHO?"

She, the world's chief doctor of the 21st century, the legendary overlord of the medical world, was killed and her soul transmigrated…She, the useless miss of the Windcloud Empire, was ugly, silly, and obsessed! She died in her own sister and fiancé's hands…When she reopened her eyes again, she had the soul of the strong but the body of the weak…When she became her, her fate would be rewritten and a miracle would appear…This was a story of a two-faced person meeting another two-faced person. With pure hearts, they would end up together.

“With my knowledge, give me a fulcrum on which to place it and I shall move the world!”

…

Sorcerer Continent—a world where sorcerers exist. Wielders of arcane knowledge. Masters of all elements. Sovereigns of space and time. These sorcerers governed the world with their unrivalled prowess. One day, a young man awakened into this world with his past forgotten and no place to call home. Follow along as Glenn, by relying on his luck and wit, tries to survive and advance in this unforgiving world. Entangled within the machinations of fate, political schemes, power struggles and wars, he forges his own path and creates a place for himself.

- Description from Novelupdates