The Hero Took Everything from Me, So I Partied with the Hero's Mother! - Chapter 13: Guild Marriage

In China’s modern martial arts society, Wu Xinghe was history’s youngest grandmaster of martial arts. He was invincible. Because of a strange incident, he was reincarnated as Qin Wushuang, a poor aristocratic boy in an entirely different world with its own set of rules. With his strong will and passion, he began his journey to pursue the highest peak of martial arts!

Being given a chance and reincarnated is nice and all, yet why do I have to become that male friend who just watches the protagonist flirting with his harem?---World: Kaguya-sama: Love Is War - Hyouka ----

The master Xiuxian failed to cross the calamity, the soul came to the earth, and became a waste fiance of the school flower. The school fiancee wants to force him to remarry, the hypocrite and uncle who is greedy for money fights for his family property, one indifferent killer kills his life … Grandpa’s disease must be cured … The proud family’s family must learn martial arts with him … These problems are being cultivated Master Lin Mu is not a problem before him!

- Description from 69shu

After a shocking reincarnation, our hero opens her eyes to a new (and messy) world the last thing she remembers is reading Lady Viper’s Vow, a dark fantasy novel about a cruel, misunderstood villainess and her path of doom. But when our protagonist finds herself reborn right in the heart of an attack, she’s moments away from a second, way-too-soon death. Just as she’s about to face the end, a mysterious “system” pops up with a single mission: Level Up or Die Trying. It’s bossy, snarky, and her new best friend. As she levels up into a borderline-cheater powerhouse, she discovers her fate isn’t to be a hero, a princess, or even a sorceress, but to protect the one person no one ever expected her to side with: the villainess herself.