Nightmare Butterfly adalah organisasi Interpol kelas S yang bertugas untuk membunuh, mereka memiliki jaringan dan kekuasaan tak terbatas. Para anggotanya sangat kuat, melebihi 1000 tentara elit sekali pun, dan anggota NB juga memiliki kekuatan supernatural. Kisah dimulai dari seorang gadis anggota NB bernama Yukishiro Hikaru.

Our world is not as we believe, we are not the only creatures who walk upon it. We aren't the only world. For Orci, the Demon Dimension, has always touched our world, letting it's horrific creatures the Daemn upon us. The Daemn have one purpose, to kill and sate their thirst for human blood. Little stands between the human race and destruction, only our protectors, the Hemis, keep us safe and ignorant of the demonic Daemns. Crescent Academy is where they train to fight, with no choice in the matter. When Ivy was dragged here, she had only one goal in mind; to escape. But her escape might just land her in more trouble than it was worth...

Two new students have transferred to Hogwarts, and both look almost exactly alike. Although, they claim to have no relation. The first is Pandora Blacksward, raised in the ways of muggles and wizards by her Squib aunt and her mother; the second of which refuses to practice magic for reasons few know. She is named for her box of secrets, stored inside her blood. Secrets she must keep at all costs, without even knowing them herself. The second, Alexandra Riddle. Voldemort's only know child, sent to gain the trust of Harry Potter and destroy the school from the inside. The success of the Dark Lord weighs on their shoulders, tipping one way or another due to their loyalties, and their loves.