Rebirth of the Nephilim - Chapter 4: No Choice at All

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

Demons in Academy of Light are described as vile, dark, cruel, evil, impure, and a whole lot of other things. At least, that’s how they’re portrayed in the game—a sacred land where demons and dark energies aren’t supposed to exist. That’s how it was supposed to be... So what the hell am I supposed to do now? Thanks to my rotten luck, my soul ended up possessing the lowest-ranking demon, the one who dies at the very beginning of the story... I’m screwed! I have no other options left... If I want to survive, I have to kill the protagonist.

The strongest King of Soldiers returns to the city of flowers, becoming his fiancée's cohabiting bodyguard!

Aric Valerian, the fourth prince of the Valerian Empire, bears many titles: The Forgotten Prince, The Whore’s Child, The King’s Bastard—names that have been spoken more than his own. Born with a crippling illness and devoid of mana or ki, Aric was a disgrace, scorned by his family and the court. But when the gods cured him and gifted him the strength to fight, Aric dared to hope. He sought glory in battle, only to be betrayed by his brother and sent to die in a hopeless war. In his final moments, as death closed in, a mysterious text appeared before him… [Would you like to change your fate?] After being given another chance, Aric embarks on a ruthless journey to claim absolute sovereignty. [Ki Circulation Mastered: Strength +10] [System Upgrade: Advanced tactical planning unlocked] [Hidden Fortress Established: Stronghold security +15%] The forgotten prince claws his way through the treacherous landscape of imperial politics, he is forced to make impossible choices, each decision pushing him further down a path soaked in blood. He learns that true power demands sacrifice, and the price of vengeance may be his soul.