The Reincarnated Assassin is a Genius Swordsman - Chapter 448

The protagonist of the collapse of the three former civilizations is Dr. Mei. What is the end of logic, the strongest brain, super intelligence, this is the story of the strongest scientist of Honkai with knowledge of the moon becoming the god of science!

- Description from novelbuddy

Noboru Chikara is a forsaken prince burdened by neglect and betrayal. Blamed for a devastating attack by his family to protect his siblings, he endures abuse and prejudice from his family and people of his kingdom alike as his family accuses him of being possessed by the very beast that attacked the kingdom. Driven by an unwavering spirit, Noboru sets out to reclaim his birthright and forge a new, uncorrupted kingdom. But when his father commits a heinous act, Noboru's quest takes an unexpected turn, propelling him into a realm beyond imagination. Follow Noboru's journey as he transcends dimensions and becomes the one who bring peace to all dimensions higher or lower and become The God Of Fiction.

She was originally the king of the dark mercenary world, killing, plundering, and looking down on the world; once reborn, she became a powerful family that shocked the continent, the “Ninth Young Master of Waste” of the Beiting family;

From then on, the elegance of the world, shake hands;

Belonging to ancient monsters, possessing a magical space, practicing heaven-defying skills, killing the sky, killing the gods, and doing whatever they want;

Cool and handsome, domineering and arrogant, leading the world to compete;

In this article, the male and female protagonists are double C, male strong + female strong, and the ending is one-on-one;

- Description from novelbuddy

I finally managed to kill the demon lord.