月落和亚晨是一对双胞胎兄妹，他们在一个与世隔绝的深山小村落里出生，被称为“分隔夜与昼的双子”。他们拥有获得特殊力量的资格，一场围绕他们的双使战斗也随之展开。 双使是一种成对的存在，被人类冠以“幽灵”、“怪物”、“怪兽”或“异形”等各种各样的称呼。它们并非人人可见，各自拥有不同的外表、性格和能力。每对双使都有一个与之缔结契约的主子，而指挥它们的主子被称为“双使师”。 许多大人在双胞兄妹开始懂事前就暗中操纵，试图夺取他们的力量，因此月落和亚晨在年幼时就被迫分离。本作故事以兄妹俩的重逢展开序幕。
日本各地出现了异空间「魔都」── 由于只有女性能从魔都的「桃」得到特异的能力， 因此便由女兵组成了「魔防队」。 某一天， 过着抑郁生活的男高中生──和仓优希 不小心闯进了突发性产生的魔都入口， 在那里，遇到了「魔防队」第七组的美丽队长──羽前京香， 而她竟向优希宣言：「我要你当我的奴隶。」
Adam's older brother was killed in a car crash a year ago. His family has not been the same since. As his parents struggle to cope with their grief, Adam (10), plagued with guilt over his brother's death feels he is all alone in the world. But everything changes the day he meets Abulele. The Abulele are ancient monsters, bear-sized. Local legends tell that they are extremely dangerous, but in fact, they turn out to be quite friendly and playful creatures. Abulele quickly becomes Adam's best and most secret friend. Together, they outsmart Adam's mean schoolteacher and beat the class bullies. But Adam's parents start to suspect he is harboring a secret, And when a government, Special Forces unit called "Thunder" appears in the neighborhood on a mission to capture Abulele things go from bad to worse. In order to save his best friend, Adam will have to get Abulele back home to its family, and to do so, he will need to put the past behind him and realize that when you truly love someone, ...
60年前，前所未有的“不眠症”袭向这个世界。无法睡着的人们在精神上一个接一个的生病。自杀、严重的暴力事件也因此频频发生，而变成一个重大的社会问题。虽然状况随着新药剂的开发，而渐渐的安定下来。但因为药剂有副作用，也因此造成20亿人的发病，间而诞生「嗜血种」这样的新生命体。之后，“嗜血种”与人类之间的战争爆发, 虽然最后以人类方的胜利收场，但是残留下来的嗜血种却还是存在于这个世界上….。最终，人类凭着人造血液及被称为“D-GPS”的嗜血种管理系统，来保障嗜血种的生存权利。 这个故事，是在人类与嗜血种共存为日常生活的舞台上进行的。
