MTL - Crossing the Other World to Build Gundam - Chapter 2 condition

In this school fantasy story set in the distant future, creatures contaminated by pollution have overtaken the land, forcing humanity to live in isolated mobile cities called Regios. One such city named Zuellni is a self-contained school in which freshman Layfon Alseif has just enrolled. Layfon reluctantly joins the 17th Military Arts Platoon led by the third-year student Nina Antalk and embarks on a series of adventures.

The top student from the Agricultural University, Qiao Mu, was digging in the experimental field when her hoe struck through to the godforsaken Tupo Village.No money, no rice, no tall, rich, and handsome guy, the aunts and the older female cousins pecked at her every day, making her meals less than satisfying with constant bread rolls, leaving her so hungry she felt faint.Luckily, the Heavens took pity and rewarded her with a tall and handsome man, who was enthusiastic and bold. His debut move was to climb straight into bed, sparking rampant gossip in the village: that Qiao girl, the third daughter, is nothing but trouble at such a young age, shamelessly bringing some wild man into her boudoir to fool around – absolutely shameless!Muniang looked to the sky and bellowed, “Alpacas! You think I'm Hello Kitty when I don't show my claws?”Make a fortune, become rich, fight off the scum, raise a husband – life became increasingly lush.

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates

When necromancers perform a great ritual to summon an undead servant, they bring a powerful vampire into their world. And now, their fate is sealed as food, but for Klaus, this is just the beginning of his adventure. In a cruel world where people will do anything for power and immortality, he is already very strong and immortal, so what's left if not start a family and have fun stepping on arrogant people through the way?