Supreme Dan Refiner of Realms - Chapter 21 - : Divine Weapons Heavenly Empire

The eldest daughter of the Li family is beautiful and sassy, ​​she took space materials to flee famine, and after going through many difficulties in war, disease and epidemic, she united with her family to regain the glory and harvested a beautiful boy.

- Description from novelbuddy

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.

Chu Qianze turned the pen in his hand in a circle and smashed it against the drum next to him, the loud drum sound resounding around him.

Facing the two people who looked over at him together, he pulled out a polite smile, which was very dazzling under the neon light.

“I’m sorry, you are ruining my eyes.”

Later:

Feeling the gazes of the people around him, the flashing lights that flared from time to time, and a few gasps, Chu Qianze’s mouth twitched: “Is this a new way to surprise people?”

***

Chu Qianze, who had just arrived in the world and was getting acquainted with his surroundings, was inexplicably pulled by a man and was held in his arms.

“I already have someone I like; it’s him!”

Chu Qianze looked at the person blankly, but saw that the other person turned his eyes away, his breath a little disordered.

“..?”

- Description from Novelupdates

I was reborn into a chaebol family.Into a time with no cryptocurrency, no internet, and nothing else.