A high school student who lived as a mob character ― Mimori Touka. During the school trip, he and his classmates were summoned to another world. According to the summoning goddess, so many best ranked heroes like S and superior ranked ones like A was very unusual.

Touka, however, was the only with the lowest rank: he was an E-rank hero, in the "failure frame" of the stepped pyramid frames. His status is overwhelmingly low when compared to his classmates. Moreover Touka’s peculiar skill — 【Abnormal State Skill】— looks like an absolute failure, so…

Like this, the former mob character and abandoned hero will absolutely become the strongest devil as he advances and strikes back.
[Description from MU]