MTL - America’s Road To Wealth - Chapter 65 Calid Island

The ordinary 18-year-old Edo, during a nighttime walk, finds himself in a fantasy world where he gains a mysterious power that could shape his destiny.

He Lang died by his own hands for the sake of his imperial younger brother’s ambition, whom he loved. He was offered to be reborn in exchange for giving up his past romantic feelings. Reborn without the burden of his romantic feelings, he brings with him a manual to new worlds. He wholeheartedly followed the instructions of the manual to complete the tasks, not knowing that the originally slag gong was blackening…
He pleaded to his affectionate Emperor brother to release him, he pleaded to the paranoid prisoner next door, but until the end he remained baffled.
In the end, he discovered that the full name of the manual was – “Slag Shou Cultivating Manual”
Σ (っ ° ° °;) っ!

- Description from Novelupdates

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.

The first time they met they had battled fiercely, just for a mere bunch of herbs. She needed it to save people, and he wanted to use it to save his own life.