Gekitotsu no Hexennacht - Volume 3, Chapter 8: Absolute Declaration of Intentions

A striking man of mysterious origin and peerless talent, he looks back at the world, in all its entirety, with utter disdain. And yet, in the treacherous and unpredictable ultimate formation of the Boundless Secular World, he guards a breathtaking ancient qin with broken strings, waiting silently for the destined one to arrive!

Doomsday comes, and human beings enter the heavenly world.
Ten years later, Yang Chen, who was betrayed tragically, returned strongly with the Tianyu bug. In this life, he vowed to make the betrayal pay the price. He has a powerful bug bonus, just like an open hang. Frightened to hear…

- Description from novelbuddy

This novel is also known as Gu Daoist Master

Humans are clever in tens of thousands of ways, Gu are the true refined essences of Heaven and Earth.

The Three Temples are unrighteous, the demon is reborn.

Former days are but an old dream, an identical name is made anew.

A story of a time traveler who keeps on being reborn.

A unique world that grows, cultivates, and uses Gu.

The Spring and Autumn Cicada, the Venomous Moonlight Gu, the Wine Insect, All-Encompassing Golden Light Insect, Slender Black Hair Gu, Gu of Hope…

And a great demon of the world that does exactly as his heart pleases!

—

*Gu (蛊) referred to poisonous insects in various cultures in South China while in folklore Gu spirits could transform into all kinds of species.

- Description from Novelupdates

The most unlike Slytherin.

There is a saying in the Slytherin common room, “The little wizard who disobeys will be eaten by the Night Stalker.”

He is the master of the stars that shines at Hogwarts, the Night Stalker who is feared by his enemies.

The glory made him the pride of Slytherin.

When the Dark Lord arrived, he said those words,

“Weapons, I need a lot of weapons.”

With a staff in his left hand and a sword in his right hand, everyone would shout for him: “Damn the Sorting Hat, is this Slytherin?”

When the stars return to Hogwarts, John Wick’s light will shine on the entire wizarding world.

- Description from novelbuddy