Keita Keita, a student in high school, has experienced a series of misfortunes for as long as he can remember. Sadly, those close to him have always met an untimely demise, leading Keita to live a solitary and unhappy life. Even his childhood friend Akane is no exception to this pattern, causing Keita to push her and anyone who tries to get close to him away. One lucky evening, while indulging in his favourite noodles at a local eatery, Keita meets Kuro, an unusual girl possessing abilities that surpass those of an ordinary human - a Mototsumitama. Kuro enlightens Keita about the "Doppeliner System," a worldwide happening that separates Terra, a life energy force, among three identical-looking individuals. Kuro, protector of the "Coexistence Equilibrium," the beings who maintain Terra's flow in the world, expose Keita to a hidden world that Keita struggles to accept. Caught in the midst of a battle for this classified world, Keita foolishly agrees to a contract with Kuro, unaware of its true meaning. Keita is now bound to her and must accompany her wherever she goes. As he questions whether things could get any worse for him, Keita confronts a reality that he thought was impossible.