When the players were exterminating the magical beasts, they had encountered an unexpected event.
A demon disguised as a player and launched a successful sneak attack. More than one player was killed.
If it wasn't for the internal communication system that could inform them of what had happened, even more players would have been killed.
However, even after receiving the news, the players had to put in a lot of effort to kill the demon.
This was a form-shifting demon. It could freely change its body's form and aura, and its ability to disguise itself was almost as good as real.
The habits of the players were imitated to perfection, and even better.
As the shape-shifting demon was very special, it was marked separately, and its body was stored in the rune freezer.
The original purpose of doing this was to collect various demon specimens, and had nothing to do with the corpse scroll.