Hero? I've Long Stopped Being One - Volume 1 Chapter 4

Reborn as a sword, he lived for hundreds of years, and then he occupied the body of a 15-year-old prince.

Luo Yi, a high school dropout in his original world, was isekai’d into the world of the Witcher 3. Starting out as a weak boy named Roy in the village of Kaer, Lower Posada, he was determined to grow stronger, no matter what it took. The first step toward becoming a legend was to kill. And his first kill was… a rooster. ‘You gain 1 EXP.’ Of course, Roy had his own cheat system like all the other isekai protagonists. His first step to becoming a legend started now…

He had served in the strongest Special Forces, Heavenly Sword Special Force. As the commando of commandos, he created the Netherworld in the western underground world and became the formidable Oriental Yama. He said, “I’m Liu Feng. I’m adept at two things: killing and saving. If I want to cure someone, even ghost soldiers can’t take him away; if I want to kill someone, God can’t save him.” Now he was the bodyguard of Yang Shiwen, who was the daughter of the richest family in Donghai City and suffered from a rare disease. Could Liu Feng save Yang Shiwen’s life with his amazing art of healing? What would happen to his double life?

- Description from Novelupdates