The Echidna (黒魔女 Kuro Majo (エキドナ Ekidona) lit. "Black Witch") is an extremely powerful magic created by the ancient powerful mage Typhoeus Oz. She appeared once in the 500 years by a girl her life long and starts to activate when the girl is 16 years old. The Echidna is the look of a new future by many magicians that perform their magic due to their rituals. They want to change the world into a life with no rituals and that everyone is obtaining their own unique magic.
According to what the legend says, the crystal lays hidden inside the girl's heart and causes an abnormal reaction which will cause phenomenal attraction, which the boys are falling in love with her for no any reason or why. The Echidna has also a huge mana which is the source of destroying the world alongside with the possessor. If the huge mana can be converted into energy it can help the cities in their development and allow the eternal prosperity, another form is also that all of them can use magic without performing a ritual.
What known is about the Echidna is the birthmark on their chest in a shape of a heart. Th Echidna is mostly popular by most of the magicians which that they can give away the dream and they will come out as hero's. To complete the dream of eternal prosperity and their own magic, they have to kill the possessor of the Echidna to complete their step. The Echidna itself is very dangerous for the possessor, which that must be sealed before the Echidna kills the possessor and will destroy the world.
Sixteen years prior of the series, after implanting Echidna's embryo, which had taken 500 years to conceive, inside Emma's heart Typhoeus Oz attempted to go into hibernation in order to replenish the magical energy he used up in the process. But then Sephirot appears, stole Emma from Oz and sealed her into a house within a barrier. After this Oz created the black cats golems like Anise and the other Black Cats Knights in order to find the girl that is the current holder of the Echidna who was hidden from him and keep her under surveillance until he regaines his full strength.
While the Echidna's body is sealed inside Emma's heart, her head is sealed on the moon.
- Echidna comes from the greek creature Equidna and shares many similarities.