As the Strongest Person, I Am Actually Left Behind!

In a different world where monsters run rampant. William, a genius mage, forged a deep friendship with the brave group and together they defeated the Demon King. However, the devil launched a curse at the last moment, causing William to become an immortal existence. Over the course of thousands of years, watching his friends leave one after another, William decided to stay away from society and live alone in the Shadow Forest. Thousands of years of being away from society made William gradually out of tune with the times and a complete laggard. By chance, he left the hut where he had lived alone for thousands of years and came to modern society. The adventure and fantasy story of the strongest magician returning to society!