I Became the Warrior of the Race I Destroyed

Introduction to the Work: I will avenge myself on those who killed me. Possessing absolute memory, I crossed over to another world and raised a kingdom into an empire, only to be met with death at the hands of one I believed to be a close friend. I thought death was the end, but when I opened my eyes, I was possessing a body being dragged away as a slave. What's worse, it was the body of a race I thought I had exterminated. Ten years after losing my life to my friend's betrayal. Too much had changed. "I must have my revenge. As much as I suffered. And more."