After being granted a second life, now-teenage Arthur Leywin—an unparalleled, ruthless king in his previous life—has finally become an adventurer with the help of his mentor, Jasmine Flamesworth. Although he is still far from his ultimate goal of becoming more powerful than in his past life, Arthur demonstrates remarkable skill in adventuring, exceeding everyone's expectations.

Meanwhile, Arthur's elven friend and Elenoir Kingdom's princess, Tessia Eralith, has also started adventuring. Due to the prolonged hostility between humans and elves, her duty is to spread goodwill and create friendly relations with human kingdoms. However, as a mysterious group threatens to harm the races' fragile relationship, both Arthur and Tessia soon find themselves becoming pivotal parts of a larger change for the better.