MTL - Reincarnation Of The Strongest Sword God - v2 Chapter 27 Celestial Secret Realm

Fifty years ago, the oxygen in the atmosphere changed, giving rise to a new form of air known as Spiritual Qi. Humans, plants, and animals alike suddenly awakened latent mutant genes and began evolving, gaining Superpowered Talents and Classes. Life took a new turn, and humanity had to adapt.Everything seemed to be going well until, fifty years later, a 16-year-old boy named Klaus awakened a terrifying Talent and Class. His awakening marked the beginning of a new era in human evolution.Unbeknownst to everyone, Klaus, who was shunned by society and dropped out of school to work for a better life for himself and his mother, was actually the last of the Nine Paragons—a being so powerful that even the heavens feared him.Watch as Klaus climbs the ladder of strength, pursuing absolute power with a single purpose: to protect and make his mother happy.

“Compared to our time, the current generation just aren’t as reliable” they said, “Still, isn’t he the son of the Hero?” How annoying.

It’s been over ten years since the battle between mankind and the demons ended. The children of the heroes who saved the world are all grown up.

One of them, Earth, was a talented man, and everyone expected him to succeed his father as a warrior and defend his country, but Earth was always wary of his father’s title.

One day, Earth is shocked to find his father’s sword, which was used to overthrow the Demon King, sealed in his family’s mansion.

Because trapped within was the ghost of the Great Demon King who was unable to pass on and continued to roam the world.

For some reason, only he could see the spirit of the Demon King, and the Demon King possessed him through the sword.

Every day, forced to coexist with the spirit of the Demon King, they live a strange shared life, when the Demon King whispers to Earth on a whim.

“I have a grudge against your father. If you want to get back at your father and the world, I’ll train you. I’m free.”

Earth receives special personal guidance from the Demon King just to get back at his parents and the world.

Then, in the coming days. The hero’s parents, the heroes of the past, the first love, the princess childhood friend, the geniuses of the era, and the world will tremble.

I just want to be different, no one can guess what I want to do, the more mysterious the more powerful.

- 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.