10 nen goshi no HikiNiito o Yamete Gaishutsushitara Jitaku goto Isekai ni Ten'ishiteta - Chapter 9, Part 11: Yuuji, exterminating the survivors in the monster village

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

An ordinary youth living in the year 2050 in the Western calendar accidentally came to a fantasy world created by the collision of magical elements and supernatural technology at the other end of the dimension…

- Description from novelbuddy

My name is Qin Jue. At only 16 years of age, I'm already the youngest person to ever become an uncle-grandmaster in the Xuanyi Mountain Sect.Also, I'm the strongest being in this entire world!But unlike other transmigrators, I want nothing to do with the outside world and wish to live a leisurely life on a cliff behind the sect, sipping wine and singing songs.That is until one day, a mysterious girl appears in front of my yard…Join Qin Jue as he deals with sneaky sects and greedy, hostile clans, all while raising a "weed" to sentience and creating heaven-defying spirit-energy "guns".

Zhang Siyi, a graduate student of architecture department went back from overseas seeking for work, he had a heated fight with his ex-girlfriend in a cafe. Angered, his ex-girlfriend was about to splash a cup of coffee in his direction but he managed to dodge it. As he stepped back, the misfortune was met by the handsome guy next table instead.

The following next day, as Zhang Siyi headed for a company interview, he discovered that the interviewer was the same man who suffered the splashing of coffee.

Hopeless, Zhang Siyi thought this work was unalterably unattainable, but that handsome man unexpectedly “disregarded past grudges” and decided to hire him. Even more, the man had become his immediate superior.

To accept Zhang Siyi by the said man, he was moved to tears with such magnanimity and kind-heartedness. Never had he realized it yet that his “miserable” fortune has just begun…

- Description from Novelupdates