The whole continent is competing for the "strongest key", but no one knows why the 999 sequences exist. Lin Chen, a young man who failed in the rankings, picked up the "trash" slime that was despised by the whole world, activated the first generation "Illustrated Book of All Things", and started to counterattack from the bottom - only to find that what he picked up was not a pet, but the "door" that had been sealed for thousands of years.
