The Emperor Wants To Marry The Doctor - Chapter 2582 Side Story 86: Not Siblings

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

Ever since the appearance of the Tower of Genesis twenty years ago, children's dreams began to change. Becoming a Hunter became the most popular aspiration.The same was true for Nathan Cole. But unfortunately, the Tower had yet to summon him. The Awakening he longed for never came.Until one day, he was suddenly summoned into the Tower. He was overjoyed—but the happiness didn’t last long.Nathan had been summoned… because of a bug.

During the Yongle period of the Ming Dynasty.

Zhang Anshi was ignorant, and he committed a heinous crime.

His brother-in-law is the prince? Oh, that’s all right!

- Description from novelbuddy

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.