Henkyou Gurashi no Maou, Tensei shite Saikyou no Majutsushi ni naru

Synopsis:

At the frontier, there was a mage known as "The Lone Demon King." Despite the fact that he was nothing more than an immortal being, the locals revered him as if he were a guardian deity. However, a magical organization that views his existence as perilous decimated him. He reincarnates as the second son of an aristocrat 200 years later and gains the most powerful magic power. “Let's pretend to be humans this time.” Despite the fact that he is a human lover, he has decided to pretend to be humans in this life instead of thinking about retaliation. He was the guardian deity of a region in his previous life, and while he is a local aristocrat in this life, he lacks common sense. He lacks the ability to relax. He is adored by his friends and family because he is the second son of an aristocrat. While he is regarded as a master of magic in the magic guild, he transforms into an "Immortal Mage" behind the scenes.