Kang Han-soo was an ordinary boy summoned to Fantasia, a world run by demons, where he spent ten years fighting his way to the demon king and finally killed him to earn his trip home. Instead the world's god hands him a report card grading his "humanity" at an F and drops him back at the very start to do it all again. Trapped in a loop of returns, Han-soo sets out to break the cycle and find out what is really steering his summons.