In scott pilgrim world and traveling to other worlds with a system - Chapter 57 - attention and feeding the Dark Spear

Almond Crowshade was the last surviving human in a dying world whose people failed to conquer the Grand Abyss Labyrinth’s 30th floor in time. The world was getting destroyed, and Almond was the last one challenging the 30th Floor multiple times despite the imminent destruction of the planet. He ultimately defeated the Floor Boss on his dying breath by achieving a true awakening, acquiring an X-rank Trait that signified limitless potential. Alas, he won but there was no home or future for what he fought. But a mysterious figure arrived there, feeling pity and amusement. “This is too precious and fun of a toy to let it rot here. You shall reincarnate and climb up to make things interesting.” [Transfer to another world commencing…] [Your memories will be sealed, and you will reincarnate in another world that has welcomed Grimworld’s tutorial like this one. Clearing each floor of the Grand Abyss Labyrinth will unlock a portion of your memories, until the 10th Floor upon which you will gain your full memories.] ‘I’m giving you a second chance. This time, you must clear the Grimworld’s tutorial and step onto the big game to make things instresting and entertaining.’ [Good luck.]

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 servant looked at the grieving princess. “Your Highness, the Regent Prince sent your scholar fiancé to the Western Butcher’s daughter!” 

The princess gritted her teeth, speaking to her servant that it matters not as she has other suitors in line. Many days later, much to her dismay, the servant ran in a hurry. “Your Highness, the Regent Prince expressed his intention of becoming your suitor! All other men in line were sold to Gou Lan Red District!”

The princess was distressed. She said to her servant it matters not. She’ll soon be married to Prince Fuma. Then the uneventful came. The servant once more ran to her, almost tripping in the process. “Your Highness, Prince Fuma was imprisoned at home! Meanwhile, there’s a red sedan chair waiting at your residence for your marriage! It was led by the Regent Prince!

The princess was stunned. For a day such as this to come, it seemed impossible. This nothing but a sad story of a female boss crossing back in time to hold the thick thighs of the big boss. But while raising him, she was eaten in the process.

Naofumi Iwatani, an uncharismatic Otaku who spends his days on games and manga, suddenly finds himself summoned to a parallel universe! He discovers he is one of four heroes equipped with legendary weapons and tasked with saving the world from its prophesied destruction.

As the Shield Hero, the weakest of the heroes, all is not as it seems. Naofumi is soon alone, penniless, and betrayed. With no one to turn to, and nowhere to run, he is left with only his shield. Now, Naofumi must rise to become the legendary Shield Hero and save the world!