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?
It wasn't tricky so much as something 
not covered yet in class.
Ein Trick? Ja, das haben wir
im Unterricht noch nicht gelernt.
No es que fuera trampa,
es que no lo hicimos.
No es que fuera trampa,
es que no lo hemos hecho.
Ce n’était pas un piège.
En fait, on l’a pas encore vu en cours.
Più che un trabocchetto,
Так почему подвох-то?
Мы просто не проходили ещё этого.