Shiraishi Tetsuya, a highschool sophomore student, who lost his family in a weird accident, always thinks about how to conquer the mythical gods whom he placed the blame upon.
Being suddenly dragged into a mess involving his beliefs and the very lives of the people around him, his whole life changes as a goddess named Setoria, a petite girl with golden hair and blue eyes, grants him a crest of her blessing for him to use in order to defend and attack against the threats that appeared in his new life.
A few months later, he finds himself completely helpless as another goddess took him under her wing through sheer intimidation and by breaking apart the very core of his ideals.
Though he was never a hero but only a man who clung onto his ideals quite profoundly, his comrades could not believe that the day would come when he would lose himself to the gods.
Thus, they shall sing the Requiem of the God Slayer, a song made for the purpose of honoring the one who has fallen.
Accompany Tetsuya in his quest to avenge his family's death and conquer the gods and the other higher beings below and beside them.