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?
Why were you the only one not 
fooled by the tricky question?
Comment t’as réussi
à ne pas tomber dans le piège ?
Perché sei l'unico che non è cascato
 nella domanda a trabocchetto?
Por que só você não caiu
na pegadinha da questão?
Почему только ты
не увидел в ней подвох?