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?
Wait, the two worlds would've 
traced different histories,
Nein, die Vergangenheit der
beiden Welten ist unterschiedlich,
No. Tienen historias distintas,
así que no puede pasar.
No. Tienen historias distintas,
así que no puede pasar.
Non.
No, non può essere.
Não, os dois mundos têm uma história
diferente, portanto, não será assim.
Нет!