Crave You Forever - Chapter 18: Yeongsoo?

A Federation Colonel with abnormal thoughts was locked in a dark room and met a little looney.

“Your whole body emits a scent that I dread (covet) and fear (desire).”

A frigid Colonel X little looney roommate: A sweet story of interstellar travel

- Description from Novelupdates

After annihilating Han, Zhao and Wei empires in succession, the dynasty of Qin is ushering in an unprecedented flourishing age with powerful cultivators emerging endlessly. People take pride in being part of the Qin dynasty. However, Ding Ning, a young lad of humble origin in Changling, Qin, is determined to subvert this dynasty and kill the emperor who breaks in the Eighth Realm.

A mecha otaku is reincarnated into another world as Ernesti Echevalier (Eru). In this world there exist huge humanoid weapons known as Silhouette Knight. Dreaming of piloting those robots, Eru, with childhood friends, Archid Walter and Adeltrud Walter: together they will aim to become a Knight Runner, pilot of Silhoutte Knight.

The prospective college student Luo Ji, who is enjoying the last summer of the third year of high school, has undergone earth-shaking changes at this moment after accepting the invitation of the game friend and becoming the player of the game of “Civilization Rise”.
This is a war game between the world and the world, and it is a fierce collision between civilization and civilization!
To annex the five continents, sweeping across the three oceans, and see how Luo Ji led his people, in this powerful enemy look around, the battlefield of the heroes to fight for a battle to the most powerful imperial civilization!

- Description from uukanshu translation