Majutsu wo Kiwamete Tabi ni Deta Tensei Elf, Moteamashita Jumyou de Ikeru Densetsu to Naru

Minoru Kido dies at thirty feeling that he left behind nothing proving he ever lived, and his next wish is granted in an unexpected way: he is reincarnated as an elf with a thousand-year lifespan. He spends the first century of his new life mastering healing, elemental, and ancient magic, then realizes he still has nine hundred years he refuses to waste inside the forest. He sets out in search of a life worthy of that time, meeting people who grow old while he remains to witness entire generations pass. As centuries move on, casual deeds become stories and stories become history, until the man who only wanted proof that he lived finds himself becoming a living legend.