One Piece: Don't Worry, I'm a Doctor - Chapter 3 - : A Master? You Want to Learn from Me?

Thousands of years ago, a small planet collided with Earth and destroyed the world. In five days, ninety percent of humans had been wiped out, leaving behind the last ten percent to earnestly struggle on death’s door.

Jinyu was one of those people who survived. Due to a special heredity trait, he could understand beast language. After the apocalyptic disasters, Jinyu had been living for a month with the few small beast brothers that he’d subdued. Previously, Jinyu had thought that he would live like that until he died. Yet, inexplicably, one day he opened his eyes to find that he was in a monstrous, lawless world that was full of vitality and life.

Jinyu’s transmigration into the future let him skip over almost one hundred thousand years. In the year 106825, beasts rule the galaxies and ‘pure’ humans are extinct. As the one and only ‘pure’ human left in the entire universe, Jinyu braves this new chaotic world to find a place for himself and thus begins to work at Beast Store number 138.

- Description from Novelupdates

I belong to a good sect that has never turned its back on me for my poor potential, has never forced me to study martial arts, and even helped arrange a betrothal for me when I was young.

My fiancée is a much renowned hot-tempered young miss. She’s beautiful, strong, and deeply loves me. Upon my start down the path of the Jianghu, I entirely relied on her to provide cover for me and before long, I became renowned as the #1 Pretty Boy of the Immortal Path.

Yet one day, I discovered that this person is apparently a man. A man in drag!

More unforgivable is that he thought I was a woman dressing as a man!

Me, as if my liver and guts are being cut to pieces: “Brother, what have you done with my fiancée?”

Him, as if a knife has been twisted in his heart: “Brother, what have *you* done with my fiancée?”

The waters of the Jianghu are indeed murky. Even if I am starving, even if I’m dying far from home, from this point on, I will not eat even a mouthful of rice prepared by him.

—So fragrant.

- Description from Novelupdates

On the brink of destruction, I regained consciousness and found myself back in the past, 20 years ago. In order to have a peaceful retirement, I must prevent the impending doom.

Chen Sansi traveled back to the chaotic end of a dynasty, thankfully with the hardworking system by his side. He originally wanted to hunt to earn money and someday go to the Martial Arts Hall to learn some basic fist and foot techniques, aspiring just to be an ordinary rich man. Yet, fate had other plans. With officials imposing heavy taxes and the Martial Arts Hall bullying the citizens, he had no choice but to enlist in the army to survive, becoming an archer. From “archery (entry-level),” he worked tirelessly up to “operating a ten thousand weight bow, where arrows cannot be dodged,” taking the heads of enemy generals from a hundred miles away! From “basic soldier’s spear technique,” he worked tirelessly up to “National Guardian Dragon Spear, growing more valiant with each battle,” standing firm with a spear on horseback, alone turning back the Enemy Army of a million! Years later, Chen Sansi, having campaigned in the south and battled in the north, was truly invincible under the heavens, commanding two hundred thousand of the Iron Cavalry. Watching his subordinates forcibly ascend him to the throne and become emperor, he felt quite helpless: ’You... you have really caused me trouble!’