The Simple Life of Killing Demons - Chapter 13Book 3:

Luis Hartmann activated the mysterious Portal and began the journey of traveling between two worlds. In Immortal world, there are various immortal cultivators who can destroy mountains and live for thousands of years. In his own world, it is a Western fantasy realm where people can become knights or wizards, with different kinds of races. Luis, using the resources of both worlds, rises through the ranks. The life seed that knights awaken when becoming apprentice knights transforms into spiritual roots in the immortal world. With strategic wisdom, he helped his family become the eternal family, dominating both worlds. [Knight + Martial Arts + Immortal Cultivators + Family building]

'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.

In a world fraught with innumerable dangers where living day by day is a struggle, a young man from the modern age transmigrated into such a world, accompanied by a peculiar system made for assassination.

In the current era, people are either normal or are with ‘special abilities’. Cases related to the latter are managed by the “National Anomaly Prevention and Control and Special Species Management Office”.
Qi Zheng Emperor Sheng Lingyuan was reawakened a thousand years later after he jumped off the fiery Red Lake. Xuan Ji, a newly transferred staff to the Reparations Division of the Deviant Control Office, finds himself having to clean up the mess of a revived tyrannical monarch. The two seemed to share something from the past, but unbeknownst to them, a big conspiracy is stirring right underneath their noses that could destroy the balance of the world.

- Description from Novelupdates