Emisarry Of Time And Space - Chapter 189: Encounter.

Zhao Rong boasts super medical and martial skills, yet he keeps a low profile as an ordinary college student. When he gets his first part-time job, which requires him to pursue a school beauty whose boyfriend is a killer, Zhao knows his peaceful life ends.

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 an unforeseen circumstance, Kayn is abruptly transported back in time, accompanied by someone he once considered his most significant foe. As he delves deeper into the past, Kayn discovers the truth behind the events that led to his betrayal by both his guild and allies, as well as the agonizing reality of being abandoned by those he was sworn to protect. Fueled by a deep desire for retribution, Kayn vows to take matters into his own hands and right the wrongs of the past, proclaiming his intent to become a Kingmaker and shape the future according to his own vision.

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.