Unserious Beast Tamer - Chapter 799 - 381: Cancan at Twelve, Double Evolution!

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates

This story unfolds during the later stages of World War II, where a man, scarred by the horrors of war, finally grasps the profound and harsh realities of the world. In this world, those at the top laugh and celebrate, while those at the bottom sacrifice their lives in futile conflicts driven by pride and meaningless ambition.A modern soul transmigrates and fuses with the original soul of a body, creating a unique and extraordinary existence. To some, he is a villain; to others, a madman.In a world steeped in cruelty, this man, determined to secure a place among the decision-makers, struggles to break free from the ranks of those powerless to control their fate. To achieve his goal, he resolves to shatter the chains of law, then the chains of morality, and finally the chains of mediocrity.

The young lord of a small and weak country saves a dragon beside the sea one day.

Ten years ago, mana descended upon Earth in the form of Gates that opened into other worlds. These Gates contained Magical Beasts of unfathomable strength and power that preyed upon humans and sought the destruction of everything around them.But along with the Gates, humans gained the power of Gifts—super abilities that allowed them to fight back against the monsters and take back their world.Now, the Superhumans with Gifts are tasked with defending the people and ensuring that the Gates, which open all over the world, do not bring about the end of them all....Jason Marc was just your regular seventeen-year-old high school student whose father abandoned him ten years ago. He worked two part-time jobs while also helping his mom with her diner to aid with the finances, but he could have never guessed that his entire world would change on the eve of his eighteenth birthday.Now, with more power than any one man should possess and an army at his beck and call, Jason works toward protecting those close to him while finding out the truth behind the emergence of the Gates—and preventing the end of the world.