While struggling to make friends after his parents’ divorce, Koyomi Takasaki meets Kazune Takigawa, but apparently, they already have. Kazune reveals that she’s from World Line 85, an alternate universe in which she and Koyomi are lovers. But in a reality where moving between dimensions is natural, could Koyomi be the one from another world?
The farther from 0 you go, the greater 
the difference in the tangible world.
Je weiter man sich von null entfernt,
desto unterschiedlicher ist die Welt.
Cuanto más te alejas del cero,
más diferencias hay.
Cuanto más te alejas del cero,
más diferencias hay.
Plus vous vous éloignez de 0,
plus les mondes diffèrent.
Più ci si allontana dallo zero,
Quanto mais você está longe de zero,
mais a diferença no mundo físico aumenta.
Чем дальше вы от изначального мира,
тем больше перемен.