High school student Amatsuki Iori was summoned to a different world to fight as a brave of salvation, but whilst he was trying to save the world, he ends up being killed by the companions whom he wholeheartly believed in. <br> It was then, when Iori thought that he already died, he came to his senses only to find that he was re-summoned to the same world, but in the future. <br> Back again as a brave to subjugate the demon king which his former self had failed to defeat previously… <br> Then, he noticed, that among the guys who ordered him to fight as a brave, the figure of one of his former comrades could be seen. <br> 「……I will make you regret having betrayed me.」 <br> A girl then appears before him as he is consumed by hatred, but not any ordinary girl – she is the former demon king who is also aiming to take revenge. <br> The brave man who abandoned his heroic ideals, exchanging them for a burning desire to take revenge and the former demon king who seems ready to join him in his new-found quest