Dresden Slate

Dresden Slate is a mysterious stone that appears to be the source of the Auras and various Sword of Damocles used by the kings.

The power of the slate could be manifested not only on humans but animals, such as mice.

History
Little is known about the Slate, but was a subject of Germany’s research during World War II lead by Adolf K. Weismann. After the bombing on Dresden, Daikaku brought it to Japan, it's currently in his possession.