A dungeon needed adventurers just like adventurers needed dungeons. After all, where would they get all their riches if not in a murder pit? Not to mention that The Core was more than happy to oblige, what with the invader's death letting it advance further than the 10th floor.

There was just 1 problem, no invader came, no matter how much it waited.

Finally, after seeing a human nearby in a wolfs memories it decided to risk it all and venture out, in search of foolish adventurers who would obediently die in its halls. Only what it saw before it was much different than what The System told it about the surface.

Where were the adventurers? Who were these cultivators? And why did no one know about the existence of dungeons?