Suddenly, "Dungeons" appear in the modern world, and at the same time, "Seekers" – those who are suited to explore these dungeons – emerge, marking a period of about 30 years. Daichi, a high school graduate working as a part-time worker, wakes up one morning to discover that he has become a "Seeker" of the dungeon. As he struggles through nearby dungeons, defeating monsters and exchanging the magic stones he earns for money, Daichi gradually improves both his combat skills and financial standing. One day, however, his life begins to change when he meets a beautiful senior Seeker, Kazune, and his dungeon adventures take an unexpected turn.