The System Favors Me Too Much - Chapter 20 - : Running For Life

The Student Council President’s Secret Laid Bare (生徒会長のセキ裸ラな秘密) is fairly standard 2D Dream Bunko fare but with an exhibitionism theme.

Basically, it’s about a guy who discovers the student council president is an exhibitionist and gets roped into helping her with that fetish.

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

'Confucius spoke not of the bizarre, the valiant, the rebellious, nor of spirits and demons.'This is the story of Mok Gyeongwoon, AKA the First Heavenly Demon - Cheon Ma, the forefather of the main character of the popular novel and manwha Nano Machine. This story is the prequel to Nano Machine, taking place 800 years earlier.