MTL - Crazy Psychologist - v2 Chapter 606 is that useful

The most dependable (sarcastic) assassin -- Gao Xuan.Developing himself with an inventory of powerful gear. A master of biding his time, backstabbing, and brutalizing weaklings.Don’t love me. Nothing would come out of this.I am an assassin without feelings.

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 ͡°)

The devilishly charming Villain’s lips curled up and said: “Kiss me, hug me, hold me.”

The cold icy beauty’s eyelashes lowered slightly: “You said you would marry me, you can’t take it back.”

The yandere youngster’s eyes were deep and dark, raising his eyebrows and laughing softly: “Other than my side, where do you still want to go?”

…… Yu Chu felt helpless and could only ask help from the Main God: “My Lord, your soul shards are always flirting with me, but I don’t want to be flirted with, what would you say I should do about it– Huh? Yeah, I really don’t want to be flirted with.”

“Hey, wait wait….. Don’t be angry, hey, don’t feel wronged either, holy crap, don’t act cute and spoiled, okay okay, I will let you flirt, I will let you flirt alright!”

- Description from Novelupdates

She was a peerless genius in the way of medicine, holding the Medicine King Cauldron in her hand.

Once she transmigrated, she became a lowly little medicine slave in dispensary.

Physicians made her life difficult, princesses humiliated her, even her fiancé came knocking on her door to break off the engagement?

What was that?!

However, she had the cauldron in her hand; the top-notch medicinal herb was in her hands. She stole rare and precious herbs, punished the slanderous, plotted against the petty, treated the Emperor’s sickness, and saved the Crown Prince.

Then, the imperial edict turned the medicine slave to a concubine and received endless doting. It was unbreakable. Wait… didn’t Prince Jun, who wielded great power in the imperial court, say she was a a detestable individual?

As the saying goes, the concubine was good in the way of medicine.

However…

- Description from Novelupdates