Fff-Class Trashero

A brief description of the manhwa Fff-Class Trashero:
The protagonist of our manga is a young man named Kang Han Soo, who entered the fantasy world After 10 years of torment, he finally managed to destroy the devil. And so the moment came when he had to go back to his old world. The local deities gave him a report card.
But there’s one catch. Even though he destroyed the devil, he was given an F grade. All because of Kang’s character. Now he’ll have to start all his adventures over again. Will our hero be able to break out of this circle and return home?