Mimori Touka, a high school student who has lived as a mob character. During the school trip, he was called to another world with his classmates. So many of the highest-ranked heroes like S and mediocre ranked ones like A were very rare, according to the summoning goddess. However, Touka was the only one with the lowest rank: he was an E-rank hero, in the stepped pyramid frame "failure frame." Compared with his classmates his standing is disproportionately poor. Nevertheless, the unusual ability of Touka — somewhat odd state abilities — seems like an utter failure, so ... like this, the former gang character and the discarded hero can become the most powerful devil as he steps forward and strikes back.