It is the year 20XX. Earth was assaulted by monsters that would come to be known as "the Enemy of Humanity." In order to deal with this threat, special schools composed of teenagers with extraordinary abilities were formed. These people, who came to be known as "the Talented," had abilities that could defy the rules of reality.

Among these people with supernatural powers was an outlier, an individual who was sent to one of these schools despite having no innate special abilities whatsoever. This is the story of our protagonist, who attempts to defeat the Enemies of Humanity through the use of intelligence and manipulation alone.

Determined to climb up the social ladder, Mary Saotome invests everything she has into what her elite high school values most: high stakes gambling.

The Great Jahy, the Dark Realm's second-in-command, cuts a frightening figure, feared and revered by all. But when a run-in with a magical girl results in the destruction of the precious mana crystal, the Dark Realm falls, transporting the newly tiny and powerless Jahy to the human world! Unfortunately, plotting the revival of the Dark Realm from a cramped, crumbling one-room apartment is no easy feat when you have rent to pay and a job to keep!

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。

故事描述男主角基克尔原本是梅卜基镇最强的护卫猎人，但他想到自己在懂事后就投身于训练，长大后也不停地接案工作，同期不是已经结婚，就是过着放荡的淫靡生活，空虚的他便向公会的受付娘艾诺梅要求让他辞职去交女朋友。