Cosmic Trading System - Chapter 1 - : Business in Trouble

Time flew by. Even though their graduation was a long time ago, after countless nights and passing through fleeting time, their story is still circulated around the quiet campus of University G. This story has many different versions, but there is one thing that everyone knows to be true. Back then, that ordinary girl betrayed the genius of the fine arts faculty and yet, his love for her still remained. For her, he nearly died in a fire. For her, he gave up his chance to study abroad. Years later when they meet again, he is successful with a new girlfriend in his arms and she is indifferent with a light and clear smile. However, unknown to anyone, her longing had begun long ago and even now flooded her thoughts…

- Description from Novelupdates

In this world, Planet Earth had undergone great changes and humanity is faced with extreme danger. Luckily, humans have something called the Heaven Dao software.

[A Douluo Dalu 2: Peerless Tang Sect Fanfiction]He awakened a unique martial soul and forged unfair contracts with soul beasts.Born in obscurity, he rose as a formidable overlord amidst the chaos.He suppressed countless prodigies of his era, his talent unparalleled.He is the true Beastmaster King, the ruler of all beasts.In the shadows, he gathered strength, advancing step by step, until he reigned supreme, unifying the continent.Whether human or soul beast, he would make all beings submit and become the sole sovereign of the land.Ending the turmoil, bringing order to the world—he would ascend to the highest throne, standing above all in an era of chaos.[Multiple love interests, no simping, mastery of strategy, seizing every advantage]

This story is centered around the man named Yi Ji-Hyuk, who has spent 1000 years in a Medieval Western fantasy-like world before returning back to the modern-day Earth. When he returns, he finds that his home is facing monster threats, and that humans with superpowers have appeared to protect the innocent people of Earth.