Demon Phantom "Dark"

This monster is called a Phantom because of its ability to appear and disappear at will. Rare even for a Phantom, Dark enjoys dark nights, and is particularly difficult to encounter. It is said to be "A Phantom of Phantoms". Furthermore, because of its slightly skewed personality, it's hard to gain its cooperation even if you do encounter one. However, because they contain the pure power of Dark, many adventurers sacrifice sleep to find Dark.