Death Toll War

About
The Death Toll War was a conflict that took place when the strongest military empire of that time, the Opiros Empire, declared war to Demon King Nighcisa. It is fearfully remembered as the most bloody war in the history of humanity, since no other war had a death count as high as in the Death Toll War.

Despite being a powerful military country, the Opiros Empire was completely devastated by the Demon King, who easily destroyed and annihilated ruthlessly everything humans possessed. The war was so one-sided it barely qualifies as a war, being closer a one-sided massacre. During this chain of events, Nighcisa was so savagely brutal and oppressive even the Gods thought it was too much, to the point Supreme God Planner was forced to intervene and create the Hero System to give humanity a chance for survival.

During the Death Toll War, at least 50% of humanity was slaughtered. If we assume that the numbers at that time were similar to those of the present, it means Nighcisa killed over 150,000,000 people.