His Breathtaking and Shimmering Light - Chapter 2249

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

Yu Linglong is the shu (born of a concubine) daughter in a general’s family. Since her mother was only a tribute dancer, her position is the lowest of the low. She used to live with her mother outside the father’s residence, and they only received some monthly money from him. He didn’t bother seeing them. But when her mother dies, she moves into the general’s residence.

The general is a very irresponsible and violent man. He doesn’t really get attached to women, just letting his lust dictate his actions. His wife is a jealous woman, who killed one of his previous concubines, because he doted on her too much. She similarly wants to get rid of Yu Linglong, in part to vent her frustrations over her husband’s cheating habits.

Because the sixth miss – the general’s legitimate daughter, was bitten by a snake, she needs detoxification. The cure was apparently getting poisoned by scorpions, to fight one poison with another. But since she’s already weak, they decided it would be better if she drank the blood of someone poisoned by scorpions instead. The general’s madam naturally decided to use Yu Linglong’s blood. During the process of getting bitten by the scorpion, the original timid Yu Linglong died of fright (and maybe poison? it’s never made clear). Then Yu Mei takes over her body.

Yu Mei is a modern woman. She was some mafia boss, so she’s very capable with fighting and overbearing attitude. She died because the man she fell in love with betrayed her and killed her. So she doesn’t trust easily afterward.

Since she took over Yu Linglong’s body, she refuses to adapt to the circumstances of a lowly illegitimate daughter, and uses her violence to fight for a peaceful life, where no one will challenge her and plot against her. Basically, she beats them up into submission. In the meantime, she acquires a tail – a very persistent prince, who only seems to stick to her harder, the colder she treats him. Did ancient men have such heavy tastes, she wonders.

- Description from Novelupdates

This is a cliché story about two young people saving the world.

A fair complexion can conceal three shortcomings, but being overweight can ruin everything. Gu Yi doesn't look bad, but her round plump figure always attracts strange looks from people. In her previous life, her marriage was mediocre, but in this new life, even as a plump woman, Gu Yi is determined to rise up!