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 then two coincidentally 
similar worlds were produced.
bis sich zufällig eine sehr
ähnliche Welt gebildet hat.
y casualmente nazca
un mundo muy similar.
y casualmente nazca
un mundo muy similar.
en ait créé un nouveau
qui ressemble à celui d’origine.
che potrebbe aver dato vita a mondi che,
 per pura coincidenza, si somigliano.
surgiu por coincidência um
outro mundo bem parecido.
И как результат
на свет появились два схожих.