Fantasy: I Can Instantly Comprehend Everything - Chapter 34

On the will left behind by the 14 year old suicide victim K:

“Taku Sugawara is the devil. Nobody should believe his words.”

When a person dies, they either die light as a feather (aka unimportant) or heavy as Mt. Tai (aka very important).

In a world where magic and divine power collide, the youngest son of Lucifer, a demon boy born with unimaginable strength, was chained and sealed away by his father to prevent him from destroying Hell itself. At the age of eight, his power became so uncontrollable that even the King of Hell feared his existence. Desperate to keep the demon's destructive potential contained, Lucifer made a pact with the great Merlin, who trapped the boy in the human realm, binding his powers with enchanted chains.Years later, with Merlin dead and a kingdom still fearful of the demon’s release, an elite group of knights, blessed by the gods, take it upon themselves to guard his prison. However, when a war between the mages and knights erupts, chaos provides the perfect opportunity for the young demon to break free.Hidden among the knights, disguised within their ranks, the demon plots his next move. But his escape is just the beginning. Hunted by both the mages and the knights, he must navigate a world where ancient gods, wizards, and warriors clash. As he travels deep into enemy territory, sneaking into the heart of the kingdom, he is driven by one purpose: freedom.Now, with his powers still sealed but his physical strength unmatched, the young demon embarks on a journey that will shake the foundation of both realms. Can the knights stop him before he regains his full strength, or will the demon's wrath bring both Heaven and Hell to their knees?As the demon hides in the shadows of the human world, a new chapter in the war between gods, magic, and demonic power begins.

This novel is also known as The Yun Family's Ninth Child is an Imp!

She was an unprecedented assassin, a trump card deadly agent, but transmigrated through into Ye City’s number one prodigious good-for-nothing young miss.

I am an ugly woman? I will break out from my cocoon into a gorgeous butterfly that will blind your snobbish eyes!

I am useless piece of heap? Lightning in my hands, I will smite you to a well-cooked crisp!

Her greed and lust for money had no end. She is lewd to the core with no bottom in sight, sworn to have love fortunes blossom all around her. However, a certain someone holding a blade in the left hand and a sword in the right hand began cutting those love fortunes one by one!

The person smiled with perked brows, “Little Ninth, it looks like I have to let you become occupied!”

- Description from Novelupdates