To ruin an Omega - Chapter 17: Mistress Of The Game 1 (M)

Just like how everyone adored heroes in their childhood, a certain young man adored those powers hidden in shadows. After hiding his strength and living the mediocre life of a mob character by day while undergoing frenzied training by night, he finally reincarnates into a different world and gains ultimate power. The young man who is only playing at being a power in the shadows, his misunderstanding subordinates, and a giant organization in the shadows that gets trampled…. This is the story of a young boy who had adored powers in shadows possibly eventually reigning over the world of shadows in another world.

“I can’t accept this! I can’t! Even as a ghost, I’m going to spend eternity cursing that your relationship will shatter like glass! Break apart like a pair of mandarin ducks that fly away from each other!” With such a persisting obsession, it would be difficult for the vengeful departed spirit to move on.

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

Died while saving his dear friend and cursing the arrogant general, Leo gets reincarnated into a world ravaged by magical beasts.Here, strength speaks for everything, and the weak are killed at the whims of the strong. Leo awakens as the lowest-tier Beast Master. Just as he was thinking he would again end up under the command of some stupid general who was the reason for his death last time, he received a gift from a mysterious entity.[Primordial Beast Dominion system]Now, surrounded by people who see him as a weakling, his journey to grow the strongest has begun.Where everyone is beating their head to make their beast grow and unlock their potential, Leo uses the system to break his limiter and grow fast and surprisingly strong.With dual talent, a broken system and a yandere sister, he embarks on the journey to rise at the top of the food chain.