Code Zulu Alpha: Nerd in the Apocalypse! - Chapter 3

The consciousness of a Great Magus suddenly returned to his original body on earth, just before he transmigrated into the magic world.

Nothing has changed, it's still the same earth.

However, when he looked at earth once more as a former great magus, he discovered earth was not as simple as he knew it to be.

Hidden magus, legendary races such as vampires and werewolves, they do exist, ruling the world through the shadows.

Faced with a former great magus, who possessed as many spells as libraries, would the earth that had been ruled by a few people be able to remain calm?

After his parents died, Alex Roth had a plan: become a wizard. Through hard work, he was accepted into the world’s greatest university of wizardry—but fate had another plan.

On his eighteenth, he is marked as one of his kingdom’s five Heroes, chosen to fight the land’s great enemy. But his brand is 'The Fool', worst of the marks.

Rather than die or serve the other Heroes like Fools in the past, he packs up his little sister, his childhood friend and her cerberus, then flees for the university in hope of refuge, magic and to unravel the truth about his land’s evil.

There’s one small problem: The Mark tries to ruin magic while enhancing skills outside of divinity, combat and spellcraft.…

…that is, unless he can learn to exploit the hell out of it.

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.

Wealthy, powerful and handsome; Gu Jingze is the cream of the crop in the entire country. Every guy wants to be him and every girl wants to be with him. His life is perfect… except that he has one tiny secret that keeps him from getting close to any woman—apparent impotency.

That is, until he wakes up in bed with a total stranger one day. The next thing he knows, he is forced to marry this stranger; a feisty and boisterous woman by the name of Lin Che.

Lin Che is an average girl whose only aim is to become a successful actress. Ostracized by her family and forced to become independent, she cooks up a scheme to attain her goal. But her plan fails and she ends up marrying this cold and seemingly heartless Gu Jingze. Not only that, she must now find her place in high society, where jealous women and devious plots lay abound – all while juggling her new career.

Two strangers under one roof: From the outset, they agree to stay out of each other’s lives, but he somehow always manages to appear during her moments of crisis. Slowly and unwittingly, Lin Che begins to find it difficult to imagine a future without him. Will their relationship grow, or is their marriage destined to remain just a contract?

- Description from Novelupdates