Greor

The highest-ranking demon known as the Demon King. A powerful demon that was sealed by a seraphim at the cost of its own life, and even while sealed, its curse was strong enough to pollute the surrounding land. It broke the seal on its own a few months before Kunai was summoned and wreaked havoc across various regions. It demanded sacrifices from the people, and one of those chosen as a sacrifice was Aku. Although Aku was a fairly capable individual, able to inflict a scratch on Kunai with a physical attack, he was no match for Kunai and was swiftly killed.