The Dark Magic Device in "Metaphorical Fantasy: ReFantazio" is a special prop in the game. If you want to get this Dark Magic Device, you can explore the Gujing Dead End during the day on July 8, and then go to the Decay In Waterway 6, save people first and then open the treasure chest. You can get it by opening the treasure chest in the north of the map.
How to obtain the Dark Magic Device of Metaphorical Fantasy
July 8th, daytime, explore the dead end of the ancient well, the plot, the decaying waterway 06/06, save people first and then open the treasure chest, otherwise you will be forced back to the center of the map.
Open the treasure chest in the north of the map near there to find the Dark Magic Device.