Koko wa Ore ni Makasete Saki ni Ike to Itte kara 10 Nen ga Tattara Densetsu ni Natteita - Chapter 199 - A Feast with the Beastkin Wolves

Everyone thought that the most powerful scientist they had ever seen was a national treasure-level scientist until they saw Baizhi-
The light of technology, a cosmic scientist.

Three thousand worlds are different.

In each world, she is keen on scientific research.

This is a story of a scientific researcher who concentrates on scientific research, explores high-dimensional science in various worlds, and refuses to admit defeat and fate. The text is easy to comprehend, flows smoothly, humorously, and the plot is full of ups and downs, and it is full of positive energy.

- 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.

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

An F-Class Hunter.

A heroine character transmigrates and gets busy expanding her golden halo of MC-ness.

A villainess character transmigrates and gets busy changing her cannon-fodder fate.

A side character transmigrates and gets busy stuffing her bottomless stomach. She holds a divine sword in one hand and a little bun in the other. She’s obedient, adorable, incredibly clueless, and frustratingly tightfisted with her words. So what does she do when she spies a cute blonde?

Feng Wu: “Please marry me!”

Ming Xi: …

A hilarious story about an overpowered airhead in a world reminiscent of Coiling Dragon. This particular tale has an interesting mash of tropes.

- Description from Novelupdates