I'm The Devil - Chapter 9: What are you the God of?

She is the slow-witted idiot of the Prime Minister’s Residence. Everyone bullies her. He is the most respected and unfeeling Prince, with frightening ability and absolute envy! Together, they are conferred an imperial edict of marriage.

She acts stupid and tries to decline in every way possible while he despotically escorts her into the wedding…… everyone ridicules the match, but no one knows that the “idiot” has transformed from a loser into a talent.

After the marriage, when they encounter the Empress Dowager examining the room, they act in concert with each other and pretend to be two mandarin ducks deeply in love. Afterwards, she laughs, “The performance has ended. Your highness, please return.”

He laughs softly, “Since you’ve got onto this Prince’s bed, don’t even think of getting off.”

- Description from Novelupdates

This story is centered around the man named Yi Ji-Hyuk, who has spent 1000 years in a Medieval Western fantasy-like world before returning back to the modern-day Earth. When he returns, he finds that his home is facing monster threats, and that humans with superpowers have appeared to protect the innocent people of Earth.

[Warning: This story contains extreme violence, philosophical depth, psychological breakdowns, self-improvement, self-realization, and themes of maturity.]“Even Gods need character development.”That was the belief Pratham lived by—struggling, always pushing forward. Until the day he died, starving in a world too cruel to care.But death was only the beginning.He transmigrates and awakens in a multiverse as Leon. In this multiverse, the greatest threat to humanity isn’t demons or beasts, but Entities. In response, civilizations across each universe forged a single hope: the Entity Hunters Organization, training warriors to stand against the impossible.He had no magic. Just his will, his fists—and a little sister he swore to protect at all costs.Enrolling in the Entity Hunters High School, Leon finds comrades, purpose, and war. He fights beside them across different planets and universes, grows with them, laughs with them—then loses them all.Leon rises not as a hero, but something else.

The ill-fated high school student Liu Yuan obtained the inheritance of the top civilization in the universe and changed his own destiny. He also used many powerful technologies in the inheritance to lead the Chinese nation to rise in the universe.

- Description from novelbuddy