After an ordinary, unremarkable life ends in a sudden traffic accident, a thirty-year-old Japanese salaryman awakens in a new world as an elf. Now named Liese Klein, he discovers he has been granted a second chance along with an extraordinary lifespan of one thousand years. Carrying the regret of having left no trace of his existence in his previous life, he vows to use this opportunity to ensure his new life will be remembered.

His journey begins not immediately, but after a long period of dedicated study. Living in an elven village, Liese spends his first century mastering every form of magic available to him. He progresses from healing magic to all elemental attributes and eventually deciphers ancient magical formulas. Once he has achieved this peak of magical mastery, he seeks permission from the village chief to leave. The chief imposes a final trial to test his readiness, which Liese successfully overcomes, finally setting him free to explore the wider world.

With over nine hundred years still ahead of him, Liese departs on a sprawling adventure across the continent. The series follows his long and winding journey as he encounters a variety of people who will shape his legend. He meets a nameless human girl, whom he names Minori, and later takes on an adventurer named Jin as his apprentice. As he travels, word of his immense power and ancient knowledge spreads. He becomes intertwined with the rise of fledgling heroes, the founding of kingdoms inspired by his deeds, and rumors of a resurrected demon lord that he may one day confront.

The narrative chronicles the life of a reincarnated elf who chose to leave the safety of his home to become a living legend, exploring how a single, exceptionally long-lived individual can leave an indelible mark on history and become the founder of modern magic for generations to come. An anime television series adaptation has been announced, bringing this expansive tale of magic and legacy to the screen.