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 was already ancient when 
your old Grandpa was a kid."
Das war schon alt, als ich noch jung war.
Ya era vieja cuando yo era niño.
Ya era vieja cuando yo era niño.
« Elle tombait déjà en ruines
quand j’étais enfant. »
Quando il nonno era un bambino
 era già bella vecchia, sai?
Quando o vovô era criança,
a casa já era antiga...
Я ещё ребёнком был,
а он уже старым считался.