Natsuko Kushinada, 18, an ordinary high school student, receives a strange necklace with a purple crystal in a dream. When she wakes up, she finds that she has The Crystal in her hand as well as the image of a mysterious creature tattooed on her right wrist. Arriving at high school, she learns that Ryuji, her cousin, has also received a crystal and a tattoo on his right wrist, as has Akira, her twin brother whose existence she did not know until today. But time is running out. These necklaces are highly coveted by a community adept at black magic called the Heirs of Azamel, led by 5 pitiful men who have only one goal: to conquer the world with the help of a creature summoned from the underworld called Cerbéga and absorb the power of the necklaces before destroying them and exterminating an enemy clan called the Kushida clan who is believed to have ties to Natsuko. But the community is also interested in Natsuko, the latter has had powers since her birth. What will Natsuko discover about her family and herself? To face her enemies, she will be able to count on the support of Nathaniel and Leila, her childhood friends who will accompany her in her fight. Will our heroes be able to overcome the community?