Neglected and abused by his stepfamily, Day runs away with his younger siblings Angie and Gray in search of happiness and Stability. 11 years have passed, now a hardworking miner, Day aims for the ambitious and honorary title of Saint Sentinel, the strongest individual in the whole continent. Day manages to get a Sentinel company even after an unconvincing trial, but now with his dreams and promises on the line and the looming threat of a mysterious organization and a legendary beast known as Ragnarok, Day will learn the meaning of hope and unity, and what it truly means, to be a Sentinel.