Knight's & Magic - Volume 3, Prologue - Silver Phoenix Knights Begin

Liola—the best assassin in his world—has vowed to kill no more. He was being chased by an assassination organization when he accidentally dropped into a parallel universe: through a dimensional gate and into poor teenager Kaiser’s apartment. Instead of going to the government shelter for lost dimensional travelers, Liola and Kaiser wind up going to school together.

Liola has been trying his best to live the life of an ordinary person, but after certain things happen one after the other, he begins to realize that being an ordinary person could be harder than being an assassin.

“I want to be a true demon.”

A boy not older than 20 years wished as he looked at the sky.

After suffering from the trauma for many years, he finally gave up on life.

People called him ugly, demon, and hideous.

He bared with it, but today he finally broke.

With a piercing pain in his chest, he died.

When opened his eyes, Logan found himself in another world and inside the body of a demon.

His wish was granted, but at what cost?

He had no power and was the lowest among the demons.

No one to help, no one to be with him.

But it did not affect Logan. Because he had something else with him.

‘Sin and Virtue System.’

Guiding him towards his goal to become a true Demon.

Logan’s conquest has begun, so be a part of it.

Otherwise, you will miss him.

The true Demon!

However, is the MC the 'only' one to have a system?

Hm?

Read the fucking novel and find out!

Beings that create and control monsters and demons, beings that build and reign over malicious labyrinths, the chosen individuals to possess an overwhelming Unique Skill… They are the Demon Lords.

Jiang Xunyi had transmigrated into a book many years ago, and always tirelessly maintained the requisite accomplishments for a villain.

After finally completing the ultra-difficult task to allow the male protagonist to kill him, an OOC warning had appeared out of the blue——

Error in the actor’s lines, the character role has collapsed, the assigned task has not yet been completed, opening the Rebirth System!

So, he gloriously became… a second idiot son about to be sent to his death.

Lazily idling away the days after changing his identity, he noticed a world-changing difference.

His best friend, the male protagonist, Yun Xie was actually secretly in love with him? Are you kidding me?!

- Description from Novelupdates