How To Obtain The Demonic Robe Similar to acquiring The Impossible Dream, you can get a Demonic Robe as a drop from a boss or by crafting it. The former will be more difficult but will take less time.

To get the Demonic Robe, you will have to fight the Heian Imaginary Demon boss enemy. It is a level 555 boss that can be fought by visiting the "Bosses" area on the map.