Strongest Survival by Otome Game’s Heroine (LN) - Vol 4 Chapter 7: Dungeon Exploration Floor 70

In order to protect my two sisters-in-law, I was possessed by a Fox Demon. Since then, I've found that the way all women look at me has changed...

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

【 Top Divine Doctor Novel, Absolutely Electrifying】Famed throughout Dragon Empire as the Sect Leader of the Holy Medicine Sect - Qin Han, unexpectedly reincarnated into another body, looked at his delicate wife and swore to redo everything, to slay the enemies behind it all. Simplicity and rudeness are my art of conduct, and 'if you don't agree, we fight' is my attitude toward life! Think you can do whatever you want with money? Sorry, my bank account balance has more digits than your social security number! Think you can do whatever you want with power? Sorry, with a wave of my sleeve, leaders of various nations queue up waiting for my medical attention! Think you can do whatever you want with people? Sorry, at my command, the entire Holy Medicine Sect springs into action! Watch how the Sect Leader of the Holy Medicine Sect dominates the Flower Capital, punches bullies, steps on arrogant youths, and unifies the forceful world!

She – a glutton without troubles or worries who crossed over and became a young fat chick with a deep vengefulness.

He – a young master of the number one power; a two-faced man with elegance and charming, good looks; he is the chosen one of the former saint god and a man who will only bend his back for her alone.

This domineering crossover’s slogan is, ‘Don’t touch if it is this sister’s, put it there even if it isn’t this sister’s!’

…watch how the Domineering Glutton and the Two-Faced Venerate Emperor create sparks as they meet and collide, stirring the whole Spirit Treasure Continent into turmoil, how they fall for each other and how they kill each other, how life and death sever love.