King Grey, a legendary monarch in a world governed by martial prowess, is suddenly murdered and reborn as Arthur Leywin in a new world of magic and monsters. Retaining his memories and the refined combat instincts of a king, Arthur quickly masters mana and becomes a child prodigy. However, peace is short-lived as the continent of Dicathen is invaded by the mysterious Alacryans and the god-like Asuras.
As Arthur transitions from a powerful mage to a master of Aether, he must decide if he will live for the glory he once held or for the family and people he has grown to love in this second life.