Rise of the Devourer - Chapter 62Book 2: — The Big Bad Ugly Pt. 2

Akira, was born in the slum and wishes to get out but the only way he could was to risk his life in these ruins as a hunter.

Between heaven and earth lies the greatest truth, and the manifestation of the great truth descends in the form of Gu.　　People cultivate the Qi of heaven and earth around their bodies to control Gu and exert their magical power.　　One year after his transmigration, Chen Qing finally discovered his special features on the day he contracted his first Gu. He was actually able to see through everything about the Gu...　　Therefore, he began to march toward the road to immortality step by step.

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

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.