Mai Kitsune Waifu - Chapter 1054 - Demon Emperor’s butt cannot be hit]

Reborn in the immortal and demon world where righteousness and evil contend, Song Yan is kidnapped into the Puppet Demon Sect and assigned as a skin-making servant.During working, his system unexpectedly awakens, allowing him to enhance his lifespan and comprehension as long as he engages in skin making.[You absorbed the remaining life span of a stubborn donkey: 10 years][Please choose the lifespan to invest][You invested ten years of lifespan to comprehend Profound Root, you continued to lie there, being penetrated by ghosts...]

Exile Ren?

The start is hell mode?

Fortunately, there are crossing benefits, and it is still a stitched monster sandbox game system!

Liver Emperor Ren? Hamster Ryan? Isn’t this basic operation?

- Description from novelbuddy

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.

In this world, mastering runes is the key to becoming a cultivator. The ability to control these runes depends on the development of one’s Brain Domain. The more advanced the Brain Domain, the quicker and more precise the rune control, determining one’s potential as a cultivator.He was a boy from the slums with slim chances of rising above his station. Despite knowing his limitations, he worked tirelessly, driven by his dream and gratitude towards a childhood friend who helped him secure a spot in a prestigious high school. However, with a less developed Brain Domain, his prospects for further education and becoming a cultivator were bleak. His hard work seemed in vain when, six months before the crucial entrance exam, the girl he cherished rejected him, claiming their worlds were too different for their paths to cross again.But then, everything changed when he found himself engulfed in a mysterious ocean of golden runes!