Gunsoul: A Xianxia Apocalypse - Chapter 59: LaChair

The ill-fated high school student Liu Yuan obtained the inheritance of the top civilization in the universe and changed his own destiny. He also used many powerful technologies in the inheritance to lead the Chinese nation to rise in the universe.

- Description from novelbuddy

Liola—the best assassin in his world—has vowed to kill no more. He was being chased by an assassination organization when he accidentally dropped into a parallel universe: through a dimensional gate and into poor teenager Kaiser’s apartment. Instead of going to the government shelter for lost dimensional travelers, Liola and Kaiser wind up going to school together.

Liola has been trying his best to live the life of an ordinary person, but after certain things happen one after the other, he begins to realize that being an ordinary person could be harder than being an assassin.

Once I’ve become Immortal, then my attempt to conquer the world shall begin.

Xue Xi is forced to fall in love at first sight with this dangerous man on their first meeting. With death being the only other option, she makes the first move: