Yuusha ni Narenakatta Ore wa Isekai de

An entire high school class is summoned to a different world. Everyone except for one boy, Sora, becomes a Hero. Unable to become a Hero, he is forsaken by the queen and banished into the void in a half dead state. Then, just before his life can run, the Demon King rescues him. The young man, having had his life saved by the Demon King, dedicates the rest of his life for revenge.