From Idler to Tech Tycoon: Earth - Chapter 37: The Day That Started It All.

Back in 1991, in the face of this golden age, Chen Jianghai swears that he will only live in three words in this life: Lin Wanqiu! The story of a reborn person who built an electrical empire and reached the pinnacle of his life!

- Description from novelbuddy

Lucien, a guy who has nothing but the desire to save his mother. To get strong enough, he makes a contract with the demon of L.u.s.t. And now, only by making a great harem, will he gain the power to protect those dear to him.

Shennugou is an old and infertile place. It’s hard to find a woman to marry here.

The Li family is extremely poor. With only four bare walls for a home, they don’t even have a woman to manage the household.

The Heavens had mercy today, Li family’s oldest son had saved a woman at the market and brought her back home.

Li Man was killed by her mother-in-law and transmigrated. She was almost hanged on the first day, but, fortunately, she was rescued by the Li brothers.

This doesn’t mean that her destiny is over.

The language didn’t make sense at first, she discovered that, here, standard Mandarin sucks.

- Description from Novelupdates

One day every human on the world suddenly receives a mail claiming to enact the World Salvation Project. Half in doubt Kurosaki Shion, a diligent university student and loner, follows the mail’s instructions, becoming one of a million Demon Kings governing his very own Domain in the new world.

*** This is a post-apocalyptic story containing many fantasy elements. It is a somewhat dark tale following Shion as he grows while aiming for the unification of the all too sudden new world. It has many game-elements bolstered by strategical thinking while at the same time providing funny moments and romantic encounters.