The Dirty Way to Destroy the Goddess's Heroes, Vol. 1 (light novel) - Asagi Tohsaka, Sakuma Sasaki

Shinichi Sotoyama might just be the world’s most average high schooler. That is, until he finds himself summoned by the Blue Demon King to a fantasy world—just like his favorite RPG games! Except this Demon King is pathetically begging at his feet, lamenting the arrival of some “heroes”…who apparently, have infinite lives and respawn over and over again?!Unlike his hysterical summoner, Shinichi coolly takes on the challenge of fending off these pesky heroes, literally shaking hands with the devil. But the demon clan is about to find out that his twisted mind is darker than the worst of them!