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?
We met as kids and you 
suffered your accident...
Seit ich dich als Kind getroffen habe
und du verunglückt bist,
Nos conocimos cuando éramos niños.
Nos conocimos cuando éramos niños.
On s’est rencontrés
quand on était enfants,
Ti ho incontrata quand'ero un bambino
Quando eu era uma criança, eu a conheci
Мы встретились в детстве,