Greatest demonologist of SSS class

Kang Min is a very ordinary guy, and on an equally ordinary day, while he was bored, sitting in class, he said that something would happen and it happened - A huge red dragon tore down the top of a skyscraper, the world plunged into chaos, waves of monsters appeared from nowhere, and half of the earth became players, including Min, everyone got the opportunity select a class.. But, My class is a Demonologis?