One Piece – Thundergod Marine - Chapter 88 Mission

I never thought I had meaning to my life, but I guess I have a talent too.

「Get ready. The duel will begin soon.」

In order to chase down and kill her own murderer, Xia Yichu reached an agreement with the 233 system, and she will travel through the world to complete the task, and The 233 system helped her return to the original world.
However, Xia Yichu often encountered a broken BOSS while he was on his way to do the task. He did n’t agree with each other on the wall, the bed, the various patterns, and kept talking.
System: Please use one word to describe the other person’s impression in your heart.
Xia Yichu: Competent.
Shen Jiaye: Mine.

- Description from 69shu

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 ͡°)

“Honey, it’s time to take your medicine!”

The beautiful and pure saintess brought medicine to treat the wound.

On this day, he saw betrayal with his eyes, and experienced despair with his soul…

From this day on, the brave is dead, burn paper if something happens!

- Description from novelbuddy