Entertainment Life With A Camera - Chapter 167:

On a harsh rainy day, a high school student without any particular special skills, Usato Ken, got dragged into another world summoning with two others; a good-looking guy and a beautiful girl, both of whom he strangely started getting along with just today. As an especially talentless individual that didn’t stand out, he thought that the others would treat him like he was useless. However, they were unexpectedly kind.———“Maybe things will be fine?”Usato who found hope in another world thought that, but the reality was different. He had a certain magic talent hidden within him and he was forced to fall into hell under the name of “training”.

“You want to steal my genes then leave?” He grabbed her and tried to force her to hand over the child that was born three years ago.

She never had a baby? Then conceive one!

The delusional CEO’s desperate love. Her inability to resist as she fell deeper.

OK, the baby is born. She handed it to him and left!

Yet, he had her hog-tied and thrown onto the bed. Furiously boiling with anger he roared, “Woman! Who said I only wanted one?”

- Description from Novelupdates

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.

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

MAIN CHARACTER GET TRANSFERED TO ANOTHER WORLD WHERE HE USE TO INCREASE CULTIVATION OF HIS WORLD