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?
And it's a world where 
Grandpa's still alive.
Und Opa ist in dieser Welt am Leben.
Un mundo en el que el abuelo sigue vivo.
Un mundo en el que el abuelo sigue vivo.
Et surtout, c’est un monde
où papy est encore en vie.
Ed è anche
E é o mundo onde o vovô está vivo.
И дедушка… здесь всё ещё живой.