Married To The Devil's Son - Chapter 246: 123:

Through a mysterious portal, Chen Jin arrived at this strange place – a post-apocalyptic world where civilization had been destroyed.

I was just your average burnout. Now I’m a kobold in a dungeon where everything wants to eat me—and frankly, I get it. I look delicious.Reincarnated as the weakest possible monster in the worst possible place, I start with nothing but panic, backward knees, and a skill called Civilization Mimicry—which is sealed. Because of course it is.But survival isn't the story.This is the story of what comes after.Of finding meaning in the scraps. Of building law from ashes. Of kindling memory in a place designed to erase.Because even if the world sees kobolds as nothing, I’ve seen what we used to be.And I’m going to bring it back.Firelight by firelight. Burial by burial. One fragile tradition at a time.Because if the world wants kobolds to be nothing?Then I’ll teach it what nothing becomes when it learns to dream.

Ruel finds himself thrust into a brutal post-apocalyptic world, bound to a bizarre “Milf System.” This system demands morally questionable acts – NTR, seducing milfs, and claiming other men's wives – as the sole means of gaining strength and essential survival skills.The brutal reality of this new world awakens Ruel's hidden lust and dark desires. He swiftly abandons any semblance of morality, embracing the system's perverse demands with growing fervor.Driven by an insatiable hunger for power and pleasure, Ruel revels in the ravages he inflicts, using his newfound abilities to dominate and conquer.His journey transforms him into a ruthless force, where survival is intertwined with the satisfaction of his darkest urges, leaving a trail of broken relationships and conquered women in his wake.

15 years ago the world discovered magic as well as mythical beings (basically beings from various legends) in another dimension. Humankind learned to summon these dangerous mythical beings and use their power to great effect. Seven countries formed contracts with these “mythical beings” and gained their allegiance as a result. The mythical beings will choose their summoners on their 14th birthday and give them a stigma. Schools have been set up to train summoners and magical swordsman (basically bodyguards that give the summoners time to cast their spell) as a result.

15 years later after the finding of magic Kazuki Hayashizaki is chosen as a summoner and given a stigma to indicate that. This is surprising since males aren’t chosen as summoners due to their low amount of mana compared to females. As the first male to be a summoner Kazuki is under a lot of scrutiny by almost everyone.

To complicate matters his sister (who’s a magical swordsman) is against him going into summoner school to train there as a summoner. Because summoners and magical swordsman have a cat mouse thing going on where summoners look down on magical swordsman as inferior so his sister naturally is against him going there. She’ll stop him even if it means going to war.

Kazuki however is determined to thrive in summoner school and has already determined to give it his all. Even if he’s the lowest ranked student (ranked E) and his fellow students intend to demean him he’ll prove himself as the strongest summoner.