Real World Dungeon

On January 1, 202X, dungeons appeared all over the world. These dungeons were both a new resource and a disaster, as monsters overflowed from them. To combat this, a new profession called "explorer" was born, who uses skills and items to defeat monsters... Meanwhile , the protagonist, who lived in the location where the dungeon appeared, wakes up in a labyrinth in the morning. This is the story of a protagonist who, hit by such misfortune, becomes stronger and survives by using his skills and magic.