Kiwameta Renkinjutsu ni, Fukanou wa Nai. Bannou Skill de Isekai Musou

Maazen, an alchemist in the twilight of his life, has poured his heart and soul into perfecting his craft. Yet, a sense of unfulfillment haunts him. In order to continue his research, he drinks an elixir of rejuvenation, which sends him into a deep slumber. Upon awakening, his finds that his youth has been restored! However, five centuries have passed, and alchemy is nowhere near what it once was. Undeterred by the negative perception of alchemists, Maazen is determined to continue his research. Armed with the long-forgotten knowledge of advanced alchemy, he navigates the challenges of this new, unfamiliar world! (Source: Square Enix)