From A Stronghold NPC To The Final BOSS - Chapter 899 - : Can’t ignore etiquette

As Shin Youngwoo has had an unfortunate life and is now stuck carrying bricks on construction sites. He even had to do labor in the VR game, Satisfy!

After a catastrophe swept across the world that destroyed half of the population and countries, a mysterious force passed through the earth that affected all residents, plunging them into unconsciousness for several hours. No one knew what it was.A few lucky people have received the revelation that the world will be destroyed in ten years. During these ten years, the world is waiting for ten disasters, and the last of them will be the end of the world.Another group of people also received a revelation that salvation is in another world. This revelation opened the way for them to another world where they could find solutions to save their home world.The rescuers were young people who were not yet twenty years old. They became awakened, able to transcend the boundaries of worlds.Idan was not among the chosen ones who became awakened. However, luck smiled on his older sister.A year after the world experienced its first disaster, Idan accepted an invitation to attend a grand ball dedicated to overcoming the first of the ten disasters.That day, during the ball, he met a young girl, and some mysterious force chose him. He awakening a mysterious system—the Supreme Husband System. In turn, the girl also received her own system — the Supreme Wife System.And so, the first task he received from his system was to propose marriage to his future wife within one day!English isn't my main language, so please bear with it if you found some mistakes.

The unparalleled Demon King Ye Xuan, who was able to heal the death or the living alike and holder of the medicine Holy Scripture, was betrayed and killed by his fellow Demon Kings. But he reincarnated into the body of Ye Xuan, the prodigal son of the Ye family and vowed to himself that he would return to his peak and take back everything that belonged to him!

- Description from Novelupdates