Johanne Green is a 15-year-old girl who lives in Golden City, the capital of West Land, the place where everyone has a guardian angel to protect them and guide them towards purification.
Johanne's mother is the mayoress of Golden City, Linda Black, who is bonded with the mightiest of all angels, the Archangel of Creation, Michael. Johanne's father, Alex Green, is the headmaster of Angel Host Academy, the greatest institution for Angel Hosts to strengthen themselves and their guardian angels. Also, he is one of the mightiest Angel Hosts, being bonded with the second strongest celestial archangel, Gabriel.
However, Johanne, no matter such powerful parents, has no guardian angel and thus is deemed dangerous and ominous to fellow people in Golden City. This makes the young girl truly sad, as she has no real friends... But she hesitates to tell about her problems to her parents who are always so busy.
However, on her 15th birthday, the situation drastically changes - the mysterious black bracelet with skulls that Johanne was obliged to wear, gives out a signal (the skulls' eyes turn red) and she is immediately sent by her parents to the East Land, to practice hidden arts of Spirit Bonding with two of her mysterious aunts (her mother's younger sister and cousin), and get to the bottom of her long-forgotten past which is deeply connected with the Demon History...