The Chairman of Pharmaceutical Company Is a Poison King

Three hundred years later, Earth was engulfed in mana. I was a “mana reject” - someone for whom mana was poisonous. One day, as I lay waiting for death without even having awakened my powers, I became connected to the same soul from another dimension. The absolute ruler of the martial arts world, the Supreme Poison Demon, Dang Gun-ak. Source: MU Includes 5 extra chapters.