"Hyung, you said you hate justice, so I guess it's not that either." "What?" "Because I want to be a good person, I immediately opened the door of my heart like this." The only survivor who prevented the end of the world, the little hero 'Seo Chae-yoon'. But now, the unknown hunter 'Yun-seo' is waiting for the day of his death. Even though he suffered from nightmares from 10 years ago that came from time to time the only reason he couldn't outright kill himself was because of the wills left by his deceased comrades. One day, with last words to live up to, the great guild Seok Seok and the No. 1 of the world 'Kwon Ji-han' brought the name Yoon Seo and the hero Seo Chae-yoon out of the world. The reason is the reappearance of the "Great Dungeon" 10 years ago, which can determine the life or death of mankind. And... 'I want to fight'? Can Yoon-seo escape her fate that is drawing closer to the end? The test 'Finding Seo Chae-yoon' starts now!