I Treat You as My Sister, But You Want to be My Wife?! - Chapter 51 - Soaring with the Boss_1

Arren was reincarnated as an extra in the book world. However, unlike the others, Arren was determined to play his role well and be the best extra ever.He was successful until that one unfortunate night that would make his second life an unpredictable one. He also began to doubt that perhaps... He wasn't the useless extra he always thought he was.R18.OMEGAVERSE/ BL

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

What would you do if you were told you only had five years to live?Aster Mistral, suffering from an incurable congenital “disease” that saps life force out of his every breath, decided to fight with all his might. Waking up into the future, 2,500 years later, he embarks on a quest to find a cure for his ailment!“My target! To find the Panacea on the 1,000th floor of the dungeon!”Together with trustworthy allies, he forges a path of blood and corpses, building his foundation and increasing his level! However, he can’t stay in dungeons all the time, as he has a duty to fulfill.“To raise the human DNA average of the world, the government wants my seeds?!”Follow Aster on his laidback journey of fighting monsters, courting girls, escaping adversaries, and discovering secrets about himself!

I had been abroad to do medical volunteer work, when I was swept up in a civil war. I was killed by a rebel soldier, while taking a bullet for a patient. But when I finally woke up, I had become a child?!?And in front of me stood a destroyed carriage and a group of oddly dressed people, who were unconscious!“It’s just like a Murim world.”As I hurry to perform first aid in an attempt to save even one person, I realize that this world is that of [The Supreme Demon King], a Wuxia novel I’ve enjoyed reading.After meeting the rescue team of the ‘Three Great Doctors’, I found out that one of the person I saved was the protagonist of this novel, the future Demon King ‘Yeo Haryun’!“Hey, since I’m indebted to you for saving me, call me ‘hyung’.”For saving his life, I become sworn brothers with the future Demon King, and the White Dragon Godly Doctor, one of the most knowledgeable people around, recognized my potential and took me in as his disciple. This is the story of how I became the greatest physician in Gangho!