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?
This is a world where 
I chose to go with my dad.
Das hier ist die Welt,
in der ich bei Papa geblieben bin.
Este es un mundo
en el que elegí ir con papá.
Este es un mundo
en el que elegí ir con papá.
C’est celui où j’ai choisi
de vivre avec mon père.
Questo mondo
Este é o mundo que eu escolhi
para ficar com meu pai.
А в том, где я решил
жить не с мамой, а вместе с папой.