Under the Oak Tree (Web Novel KR) - Chapter 229

An Individual from Earth finds themselves in the Shinobi World, equipped with a Scientific System. From that moment, he delved into scientific research far ahead of its time.

A surgeon accidentally got the blessings of a system, shocked the medical industry, and rejuvenated countless people.

- Description from Novelupdates

The young lord of a small and weak country saves a dragon beside the sea one day.

Marauders shot Yuan in the head and buried him in a ditch. They thought it would be enough to put him down. They were wrong.Rising from the dead by the will of the Gun, demigod of revenge and firearms, Yuan only has one goal in mind: track down his murderers across the Unmade World and slaughter every last one of them. With the bullet-core stuck in his skull marking him as a Gunsoul, he can finally teach these arrogant cultivators a lesson they’ll never forget.But revenge isn’t so easy to claim. To carve out a path through the wasteland, Yuan will have to face power-hungry sects, nuclear cultivators, and weapon-gods. Let them come. No one will bury him again.He’ll give them all a taste of Bullet Hell.