Goinkyo Maou-sama no Kaerizaki: Totsujo Wakagaetta Sensendai Maou-sama wa Choppiri Ecchi na Nazo Bujutsu de Joson Danpi no Sekai wo Heitei suru

A sudden bolt of lightning hits an old man...but! The lightning bolt rejuvenated him to the good-looking guy he was in his prime! His name is Gigi Allegarcia. He was called "the strongest who surpassed the strongest" and "a man who was loved by everything but magic"...he was the demon lord of the previous generation.

(Source: COMICSMART, translated)