I Am the Nanny of the Villain - Chapter 135:

*********“You will become an immortal cultivator, right?”“Yes, mother. I promise,”*********An old cursed building with many trials,A system that helps with cultivation,A bloodline that was envied by many,With the help of these three things, a young man named Henrick wanted to fulfil a promise he made to his mother.However, there were many cultivators that were after his bloodline who would do anything for his bloodline.Follow Henrick to see whether he can fulfil his promise with the world full of enemies or will he become a stepping stone for others?.

Magic, eastern fantasy, cultivation, scientific technology…

Dual cultivation isn't a choice; it's a necessity.

After being struck by a truck like most lucky protagonists (or unlucky ones), Vaan found himself transmigrated into the body of an orphan in the world of witches and demons.

However, they didn't always exist.

Demons terrorized the world ever since the Gehenna Realm descended over 300 years ago. but along with them, came mana, giving birth to witches to combat these demons.

Since then, the world of men was dominated by witches, establishing the seven witch kingdoms, which safeguards at the forefront of the demon invasion.

In order to survive in the matriarchal society of the witch kingdoms, Vaan, like all other men who cannot use magic, had to learn how to service the witches to survive.

Nevertheless, it did not come without its own benefits.

Years of research have led the world to the discovery of intimacy between men and women could increase the witches' mana absorption.

But at the same time, men could absorb some of this mana to improve their physique and lifespan.

Thus, since then, an intricate relationship was formed between men and witches in the red-light districts. Love became casual, and dual cultivation is common.

As a prodigy in the art of pleasing women, Vaan lived a smooth two years since his transmigration as an orphan.

However, everything came crashing down in a heartbeat one day when his life was nearly taken, and Lady Eniwse whom he served went berserk.

Even so, that was not the end.

With the awakening of the Witch Hunter System, watch how Vaan takes on the world and becomes the lord of witches.

=====
Note: Contains lemons.
Hunting witches does not necessarily imply killing witches if you know what I mean ( ͡° ͜ʖ ͡°)

This novel is also known as Cultural Invasion into Isekai

A group of dragons are watching “Game of Thrones” day and night

High Elf and Druid are in tears after watching “Hachi: A Dog’s Tale”

Humans​ and Dwarfs are greatly spending money on “Hearthstone”

Even the god personally arrived in the mortal world to read “Sherlock Holmes” novels.

Eventually, a great Druid has started a “pick and drop” business, all Dwarfs and gnomes have joined for the construction of internet stores.

A cultural invasion in different world from earth!

- Description from Novelupdates