MTL - Rebirth of Hong Kong’s Glorious Era - Chapter 47 Opening ceremony

Office worker Leon is reincarnated into a particularly punishing dating sim video game, where women reign supreme and only beautiful men have a seat at the table. But Leon has a secret weapon: he remembers everything from his past life, which includes a complete playthrough of the very game in which he is now trapped. Watch Leon spark a revolution to change this new world in order to fulfill his ultimate desire…of living a quiet, easy life in the countryside!

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

In this story, a regular guy from our world becomes a young Main Branch heir of the powerful Hyuga clan in the Naruto world.He's primarily interested in gaining more power and doesn't care about right or wrong. He uses his knowledge from Earth and the Naruto show to get ahead, using his creativity and intellect to the utmost.As he tries to become more powerful, we see sides of the Hyuga clan and ninja world that weren't shown in the original Naruto story.He looks into the secrets of his ancestors, the Hyuga's eyes, and how ninja politics work, finding out things we never knew before and that the original author left unexplored.However, gradually, along the way, he also meets new lovers, friends, subordinates, and enemies and challenges how things are done in the ninja world - and also tries to unify it in the process and bring real peace around.

Xuanyuan was reborn into a strange new world where training to be a Xian was a cornerstone. There was however something ancient dwelling inside his body. He could now devour all of creation…

This is the journey of an ordinary boy and his transformation into the supreme being that reigns over all existence! Everywhere he went, he could not help but tie his fate with numerous women. It did not matter whether they were a goddess or a devil…

- Description from Novelupdates