The world immediately tried to become a ruin, where a portal or what is now called a dungeon appeared. Requires several human beings who have been given the power by God to eradicate the monsters in the dungeon. And an agency emerged containing people with superpowers, an academy specifically for powers training, and even a caste according to powers. The lowest caste starts with people who have rank E powers, then the highest is rank S, but rank S is very rare, and even if there are they belong to the government/an agency heads.

One day, when you are on a rank A dungeon raid with your team because you happen to be a rank A, to get crystals and sell them. Suddenly, you are overwhelmed against the final boss. Your entire team is dying and fainting, only you are still conscious even though you are injured. From behind, a tall man appeared who looked relaxed walking into the final boss's area while smoking, he was an S rank. He was assigned to enter the dungeon to fight this final boss who turned out to be S rank.

"Is the A rank team only this strong? It's really bad. And I didn't expect an S rank boss to be in an A rank dungeon." He said with a smirk and arrogance, then put out his cigarette, took out his sword to attack.