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?
Among the many worlds derived from 
two worlds that were far apart at first,
Unter den vielen Welten, die aus einer
weit entfernten Welt entspringen,
De entre todos los mundos lejanos
que se generan,
De entre todos los mundos lejanos
que se generan,
Il est probable qu’un flux de mondes
dérivés d’un monde éloigné,
Un giorno, all'interno di vari mondi derivati
 da un unico mondo lontano,
Acho que num mundo distante que nasceu
entre vários outros mundos de escolhas,
Что, если среди мириадов миров,
порождённых двумя другими удалёнными,