The protagonist fell into an underground dungeon that suddenly appeared at his feet. Since then, dungeons have appeared all over the world, causing widespread chaos and confusion. A ranking system appeared for all 7 billion people on Earth, revealing the existence of magic and skills, further adding to the turmoil. 'Dungeon Adventurers,' who use magic and skills to eliminate monsters, have risen to prominence. However, the protagonist, unaware of these changes, enjoyed exploring the dungeon, unable to return to the surface. After successfully conquering his first dungeon, he returned to the surface and was called the 'Number 1 Adventurer' and 'Single Adventurer'. This is the story of the protagonist who delves into various dungeons, upholding his motto. *The web novel is complete.*