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?
I don't know what will happen, 
but let's keep this a secret for now.
No sé qué pasará,
pero mantén esto en secreto.
No sé qué pasará,
pero mantén esto en secreto.
Je ne peux pas prédire la suite,
mais gardons tout ça pour nous.
Non ho idea di cosa succederà,
 ma per ora non dire niente a nessuno.
Eu não sei o que vai acontecer, mas vamos
manter isso em segredo por um tempo.