Dxd: A demon Among Devils - Chapter 29: []:

Anger. Pain. Desolation.

William Hunter was a young high-school student who was constantly bullied and made fun of by the people around him.

Suddenly, one day, everyone was given a system and transported into a parallel apocalyptic world filled with powerful hordes of zombies, wrecking havoc on everyone and everything. Even with systems, most people struggle to survive.

[You have received the ???-rank system, Minion Controller]

[You have received 1x Woodcutter Minion and 1x Warrior Minion]

[You can buy more minions in the Shop]

What was this?

[Your Woodcutter Minion has collected 21 wood, it is now level-2]

As other people struggled to survive. William would be able to create an army of minions and take over this hellscape

Lu Zhiguang is not a cannon fodder himself, but his mission is to save the miserable cannon fodder.

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 ͡°)