Versatile Mage: I, the Holy Lord, the Demon Emperor!

I, the Holy Lord, the immortal god, the immortal monarch, the head of the eight demons! Because the world is too boring, I sealed myself and fell into a deep sleep. I don't know how many years have passed, but a small voice woke me up. "A great existence, the ancient capital is in danger, and the ancient king is about to resurrect and conquer the world!" "I implore you to save this country that once belonged to you!" I opened my eyes, looking down at this strange "magic" world and the vast army of undead outside the city. Ancient king? An undead man who plays with corpses dares to become king? "Mortal, what you awaken is not the savior." I took one step forward, the flames burned the sky, and the power of the dragon enveloped the entire land. "But the former, only, and true master of this planet!" "Now, keep your eyes open and watch carefully. What does it mean to be called an emperor?"