Monarch of Gluttony: System of Sin - Chapter 201: 201: Gauge of Strength

Ryouma Takuma, a 39 year-old man with a hidden past, finds himself in a strange white room. There the gods tell him that he has died and that they are sending his soul to a different world; a world where magic exists. After living alone for three years his gamer soul loses common sense and starts toward crazy routes.

Before going to college, an ordinary high school student went to celebrate and got drunk. When he woke up, he found himself in a completely different world. There was a big sect, the approaching sect entrance examination, a slum where his body’s previous owner lived, and a shared memory about a missing young girl.

When he got tangled in a fight with a few punks in this different world, he fell off a cliff and miraculously found himself still alive, with two more voices ringing inside his head. They were Sword Master and Saber Master. In the company of them, he continued to find out more about this whole new world. He took the sect entrance examination, entered the sect, met a strange man in black, and even participated in a major competition of the sect to have a chance to win over his peers!
In this whole new world, he was born again and got to explore the fantastic martial world!

- Description from Novelupdates

As the grandmaster who founded demonic cultivation, Wei WuXian roamed the world in his wanton ways, hated by millions for the chaos he created. In the end, he was backstabbed by his dearest shidi and killed by powerful clans that combined to overpower him.

He incarnates into the body of a lunatic who was abandoned by his clan and is later, unwillingly, taken away by a famous cultivator among the sects—Lan WangJi, his archenemy.

This marks the start of a thrilling yet hilarious journey of attacking monsters, solving mysteries, and raising children. From the mutual flirtation along the way, Wei WuXian slowly realizes that Lan WangJi, a seemingly haughty and indifferent poker-face, holds more feelings for Wei WuXian than he is letting on…

A mysterious natural phenomenon caused the Earth to be plunged into darkness. The world turned into an endless bloody chaos and mankind is on the brink of extinction…