MTL - Marvel: Start with Summoning the Shadow Troopers - Chapter 168

When 18-year-old Kyle Conner arrives at his aunt's for a summer holiday, he expects relaxation and freedom. Instead, his life is forever altered when he crosses paths with Lilith, the demon of lust and second-most powerful entity in the underworld.Forced into a dark pact, Kyle is transformed into a demon and gifted with a mysterious system that promises immense power. But this newfound strength comes with a deadly price: Kyle must hide his true nature and navigate the treacherous world of demons, all while being hunted by Lucifer and other malevolent forces.As Kyle struggles to control his newfound powers and unravel the secrets of the system, he discovers his ultimate goal: to overthrow Lucifer and bring about a new era of peace. But with the forces of darkness closing in, Kyle must confront the darkness within himself and make impossible choices to survive.Will Kyle be able to master his demonic powers, outwit his enemies, and fulfill his destiny? Or will the weight of his newfound responsibilities consume him, dooming humanity to eternal darkness?

I spent my life playing a game.
I hit the wall, stuck in second place for the rest of my life.

Out of the blue, I received a message and was possessed by the game.
As the worthless son of an Underworld Boss!

“Yes, bloodline is also a power, as long as you can use it. My ability is ‘Famiglia’.”

The game addict never disappears. Overwhelming violence, endless wealth, connections in the other world. I, I’ll use anything to stay alive!

The notorious imperial court lackey and the meritorious military general were well-known for their mutual dislike, a pair of arch-enemies set in stone. Who could have foreseen the unexpected change in the winds of heaven: the general injured on the battlefield, both legs disabled, and even forced by the emperor to marry his nemesis.  

With one marriage edict, two people with mutual hostility are forced to marry and live under the same roof. Yet after these long days together, they come to the realization that this fellow is not truly devoid of any saving grace/unattainable and high out of reach.

- Description from Novelupdates

A hundred years ago, he was a genius of the Emperor's Domain who made even the God of War wary. He was unparalleled in both alchemy and martial arts. However, his friend betrayed him, leading to his untimely demise.A hundred years later, he rose from being a dandy young master, starting everything anew. From then on, the world witnessed the emergence of an extraordinary genius.“Boss is even more ferocious than a wild beast!”“Boss values friendship above all else. He is forever my best friend!”“Kevin, no matter how long it takes, I'll wait for you. I won't marry anyone else!”“Don't ever provoke that man of calamity. That guy is a beast!”“I am Kevin Anderson, who dares to defy me?!”