Harry Potter with Technology System - Chapter 6: Master of Manipulation

The hero who was killed by the demon king ended up reincarnated as the son of the one who killed him! Thus began the life of the hero who donned in the mask of the ideal demon prince to topple his own kingdom while doing his best to prevent anyone from discovering his identity―― But to do that and blend into the demon tribe society, he had to kill his former comrades. Nevertheless, to become stronger, to save humanity, he had to walk through all kinds of paths of carnage! This is the tale of the demon race’s fake prince destroying his own kingdom.

O Hero, Trample Those Who You Should Protect!

TN: Most part of the other character in the novel is depicted from a non-human perspective so expect something that is completely different from the common sense of human.

“THE NEW GATE”, an online game that trapped its players and turned into a death game, was now releasing the thousands of players that had been dragged into it, thanks to the efforts of Shin, one of the most powerful players. But after having defeated the last boss and freed everyone, he was swallowed up by a strange light and found himself inside the game world 500 years in the future and unable to leave.

In novels with a stud there is always a Senior Martial Brother like this:

In the early stages of the novel, his innate talent is high, his cultivation is good, his appearance is handsome, and he has an intelligent, cute younger Martial Sister as a fiancée.

In the middle stages of the novel, he is caught unprepared and defeated by a young disciple (the protagonist) in the sect who’s hardly remarkable at all. From then on, he falls from his godly altar and loses his brilliance. Even his young Martial Sister leaves him for someone else.

In the late stages of the novel, he continues to turn dark, going down the Demonic Path and becoming the major villainous boss. However, the protagonist still ruthlessly defeats him and his soul is eternally sealed.

Once Qin Mo opened his eyes, he discovered that he had become this Senior Martial Brother.

- Description from Novelupdates

Kim Taejune, wanted to be a “hero,” a “savior” to all the weak. After reading books about them, he too wanted to be one. Yet he lacked power, he didn't have any skills, and the command system everyone else had but one day, his dream will come true. His path leads him to encounter Yoon Harin a woman who after the death of her twin younger brother Yoon Jiho was transmigrated into his novel, “Calamity Hunter” the “god” of this world makes a deal with Yoon Harin to bring her brother back to life IF she can survive as a savior till the end.