Isekai Maou to Shoukan Shoujo no Dorei Majutsu - Volume 12 Chapter 5 part1

Orphaned at ten and betrayed by his guardian at nineteen, the protagonist's life spirals into darkness, yet some light remains, only to be cruelly extinguished when his girlfriend sacrifices herself during a brutal demon attack.As a result, he is bestowed with a mysterious system that imbues him with the strength, making him dedicate himself to eradicating demons.Upon defeating the Demon King, he is granted a reward and chooses to reincarnate into a novel-like world with sealed memories until age thirteen.Reborn as the second son of a Duke, he yearns a peaceful life and respite from his tumultuous past. However, fate has different plans.In a world full of political games and supernatural dangers, he finds himself caught in conflicts involving a transmigrator villain and a regressor protagonist.Amid noble family ties, surprising friendships, and veiled threats, he must find his way through this new life, all the while dealing with lingering scars and the chaos that threatens to engulf him and those around him.Can he truly find solace in a world determined to pull him back into the fight?Will he succeed in forging a relaxed and slow life amidst the relentless anomalies at every step?Read to find out!!

In the Sky Sword Continent there are thousands of sects and strong cultivators as common as trees. In order to prevent his older sister from being forcefully married off, Lu Xuan had no choice to but to unceasingly cultivate and enter a sect to ask for a favor. By chance, a sword-shaped crystal of mysterious origins entered into Lu Xuan’s body, containing countless top-class martial skills, powerful martial arts, and everything you could wish for! A martial legend starts here…

- Description from Novelupdates

I made a game.

He possessed the Xuan Gate Medical Arts and had fortuitously obtained a heaven-defying Spiritual Treasure!