Level 0 Demon King Becomes an Adventurer in Another World

Ishuto was the strongest Demon Lord in the Dark Continent until he was defeated by the heroes. But instead of dying, he reincarnated into another world as a young man, while still keeping his powers. "I will start from scratch in this world and this time it'll be mine!". The elite adventurer Airis was charmed by Ishuto's strength and became his...