Bonded Summoner - Chapter 26Book 4. : Victory Feast

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

Emily Molson, PA to Derek Haven, CEO of Haven Group has nightmares every night, that prevent her from getting a good night's rest.Derek Haven, on the other hand is lucky to get any sleep at all. The two of them work close together but have no idea that they have the same problem.Then one night they end up in bed together and a miracle happens.

Village woman Su Xiumei, “Fei, sister is ill, come help sister with a treatment!”Lin Fei gave a wicked smile, “Xiu Mei sister, don't lock your door tonight, I'll come give you a shot and you'll be fine!”Su Xiumei, “You little rascal, you're really naughty!”

As 21 years old Noah closes his eyes for what he thinks will be eternity, he wakes up in the body of a girl 7 years younger than him.Vasilisa, as she is known, is hated and mistreated by the people around her because of the Muddy Tongue curse which not only impedes her speech, but makes her magic unstable.This effectively makes her the harder than hard mode when it comes to reincarnation, and, of course, fate made her his “avatar” in this new world full of mechanics he only ever saw in video games.Despite this, Noah as decided…Whether as Vasilisa or himself, this time he will find a way to exist for the world.